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⟦4c801b7a2⟧ Wang Wps File
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Notes: PC/PDS/001 - ISSUE 2
Names: »6213A «
Derivation
└─⟦05b6108d7⟧ Bits:30006238 8" Wang WCS floppy, CR 0624A
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WangText
A…08…A…09…A…0a…A…00…A…06…@…0c…@…0f…@
@…07…?…0b…?…0c…?…0e…?
?…06…>…0d…> =…0b…=…86…1
…02…
…02…
…02…
…02…PC/PDS/001
…02…851001…02……02…
PROTOCOL
CONVERTER
PACKAGE
DESIGN
SPECIFICATION…02…ISSUE
1.2…02…
PC
4.2.6 C̲C̲I̲S̲ ̲L̲o̲w̲ ̲L̲e̲v̲e̲l̲ ̲P̲r̲o̲t̲o̲c̲o̲l̲s̲ ̲(̲C̲L̲P̲)̲
4.2.6.1 F̲u̲n̲c̲t̲i̲o̲n̲a̲l̲ ̲S̲p̲e̲c̲i̲f̲i̲c̲a̲t̲i̲o̲n̲
The CLP package is responsible for data communication
between the CR80 and the GRTS software in the DN355/DN6678
front-end processor on the CCIS side.
CLP is implemented in the CR80 LTU and the CLP SW therefore
has to be down-line loaded from the CR80 memory during
initialization of the LTU.
CLP communicates with the GRTS using the following
three types of subsegments:
- S̲e̲r̲v̲i̲c̲e̲ ̲M̲e̲s̲s̲a̲g̲e̲s̲ for opening and closing the line
- C̲o̲n̲t̲r̲o̲l̲ ̲M̲e̲s̲s̲a̲g̲e̲s̲ for delivery of passwords and other
control data.
- I̲n̲f̲o̲r̲m̲a̲t̲i̲o̲n̲ ̲M̲e̲s̲s̲a̲g̲e̲s̲ used during the transmission
of data segments
In this context the term "messages" means the various
subsegment types sent between the CLP and GRTS including
header and trailer characters.
Due to the half-duplex nature of the communication
link the sets of messages sent from the two sides are
not symmetrical. Therefore, a description of the possible
messages sent from either side of the link is given
in Figure 4.2.6.1-1 and 4.2.6.1-2.
FIGURE 4.2.6.1-1
SERVICE/CONTROL MESSAGES
FIGURE 4.2.6.1-2
INFORMATION MESSAGES
In the above figures the nomenclature of References
6 and 18 is used:
"Remote" = CR80 LTU
"DN355" = DN355 or DN6678
SYN = sync. character, #16
SOH = start of header, #01
FC = varying function code
SC = sequence code alternating at
each side between #41 and
#42 for each message sent except
for IRD2 for which it is constant.
AC = address code, #40
OC = operation code. OC.(2:3)
(bits 2,1,0)is a three bit
field holding the operation
code. OC. (5:3) (bits 5,4,3)
is a three bit field with the
binary value 000 for acknowledge
or 001 for negative acknowledge.
IC = identification code #40
AUX = auxiliary field, #47 (only
used in "Select", SRD3).
STX = start of text
MC = media code…06…1 …02… …02… …02…
…02…
TEXT FIELD
a) from 1 up to 324 bytes of data sent to GRTS
using the IRD3 and/or IRD4 messages.
SUPERACK's, SUPERNAK's, and BUST messages will
be sent as IRD4 messages.
b) 1 to 324 bytes of data received from GRTS in
IDR3 and/or IDR4 messages
c) $*$LOGID$PSWRD/DNM
where ID and PSWRD are two character strings
with lengths from 1 to 12 characters each ̲supplied
from CR80 together with the OPEN LINK command
d) LINE DISCONN. XXX and LINE TERMIN. XXX stands
for:
LINE DISCONNECTED XXX and
LINE TERMINATED XXX.
'XXX' is a character string of two or three
characters.
e) (*) DINDAC and (*) RSTRT are two optional character
strings. One of them is received during an
OPEN LINK sequence in an IDR2 subsegment. One
of them is sent from CLP in a TIRD2 message
when simulating DINDAC during tests.
(*)should be read as the hexadecimal characters:
#3C, #2A, and #3E. Cf. Reference 3, p.3-A-4-2.
RS = record separator
ETX = end of text, no more subsegments in
segment
ETB = end of text, more subsegments will
follow to complete the segment
BCC = block check, i.e. ex-or of characters
following SOH and including ETX. Denoted
"**" in the figures.
AL = alternating independently at both sides
between #41 and #42.
C0 = constant and equal to the previous
value used. The first "WAIT" segment
has a SC field equal to the previous
message sent.
DA = alternating differently compared to
"AL" in the usual SRD, CRD, and IRD
messages. Messages with SC equal to
"DA" are used in simulation of GRTS
with values of #41 and #42.
All numbers in Figures 4.2.6.1-1 and 4.2.6.1-2 are
hexadecimal except for the "SC" column as explained
above. Unused fields are marked "-- " and "---".
CLP recognizes incoming messages from GRTS and assigns
a constant value taken from the constants declared
as "grts ̲messages" in section 4.2.6.3
F̲u̲r̲t̲h̲e̲r̲m̲o̲r̲e̲, each incoming message is checked for the
occurence of one of the following events:
- OC.(5:3) = 001 (binary) and the SC field is changed
from SC of the previous message and characters
are present in the text field. This is an implied
ACK.
- OC.(5:3) = 001 (binary) but the message is not
an implied ACK.
- the incoming message contains an error. Check of
messages is described in subsequent sections. Checks
are performed according to References 6 and 18.
CLP is able to send the messages denoted SRD, CRD and
IRD as shown in Figures 4.2.6.1-1 and 4.2.6.1-2.
Any of these messages may furthermore be retransmitted
any required number of times.
Retransmission is performed with the SC value equal
to the one of the previous message sent.
For ordinary messages and frames to be retransmitted
the ACK/NAK field, OC.(5:3) is set to either 000 or
001 (binary).
Functionally, the CLP is divided into an OPEN LINK
sequence and a DATA TRANSMISSION sequence.
A state/event description of each of these sequences
is given in section 4.2.6.1.1 and 4.2.6.1.2, respectively.
4.2.6.1.1 O̲P̲E̲N̲ ̲L̲I̲N̲K̲ ̲S̲e̲q̲u̲e̲n̲c̲e̲
a) S̲t̲a̲t̲e̲s̲ ̲i̲n̲ ̲O̲P̲E̲N̲ ̲L̲I̲N̲K̲ ̲(̲S̲O̲L̲)̲
SOL0 Initial state entered after power-up/masterclear
and bootloading.
SOL1 Before sending RFD to GRTS.
SOL2 Before sending SELECT to GRTS
SOL3 Before sending ID and PSWRD in LOGON message
SOL4 Before sending $*$DACDINDAC in LOGON message
SOL5 Before sending ACK on DINDAC or RSTRT message
SOL6 Closing state
SDT0 Starting state of Data Transmission sequence
b) E̲v̲e̲n̲t̲ ̲c̲l̲a̲s̲s̲e̲s̲ ̲i̲n̲ ̲O̲P̲E̲N̲ ̲L̲I̲N̲K̲ ̲(̲E̲O̲L̲)̲
EOL0 start ̲protocol, open ̲link ̲timeout, naks ̲exceeded
or logon ̲error is true. Cf. section 4.2.6.3
concerning the use of these variables.
EOL1 CR80 OPEN LINK command
EOL2 CR80 CLOSE LINK command
EOL3 READY FOR DISCONNECT, SDR1
EOL4 TRANSMIT DATA, IDR1
EOL5 DINDAC or RSTRT, IDR2
EOL6 Bits 5,4,3, OC.(5:3) is NAK. No text field
is present and/or the SC field is constant.
EOL7 Bits 5,4,3, OC.(5:3) is NAK and SC is changed
and text is present.
EOL8 Message is in error. Message checking will
be performed during analysis of input according
to Reference 18.
EOL9 Disconnect SDR2
EOL10 Line Down Control message, CDR1
EOL11 Other events
c) A̲c̲t̲i̲o̲n̲s̲ ̲p̲e̲r̲f̲o̲r̲m̲e̲d̲ ̲d̲u̲r̲i̲n̲g̲ ̲O̲P̲E̲N̲ ̲L̲I̲N̲K̲ ̲(̲A̲O̲L̲)̲
AOL0 Initialize variables, reset and start timer
if power up then initializes the message counters.
AOL1 Read and store the userid/password and baudrate
from CR80. Set baudrate according to value
given in OPEN LINK command. Send READY FOR
DISCONNECT, SRD1.
AOL2 Not Used.
AOL3 Update open ̲link ̲timeout. Send SELECT, SRD3.
AOL4 Update open ̲link ̲timeout.
Send LOGON with userid and password previously
read from CR80, CRD1.
AOL5 Update open ̲link ̲timeout
Send LOGON with $*$DACDINDAC, CRD1.
AOL6 Reset OPEN LINK TIMEOUT.
Answer pending OPEN LINK request from CR80.
If line ̲down ̲message ̲code NE OK return this
value as result to the CR80.
Set flag for ACK ̲TO ̲BE ̲SENT:= TRUE
AOL7 Update open ̲link ̲timeout. ACK/NAK field of
previous message sent is set to NAK and the
message is retransmitted without altering the
SC field.
AOL8 Update naks ̲exceeded and open ̲link ̲timeout.
Retransmit previous frame with same SC and
ACK in the ACK/NAK field of OC.
AOL9 Answer pending CR80 OPEN ̲LINK command with
reason code for closing. Send DISCONNECT, SRD2.
AOL10 Answer CR80 CLOSE ̲LINK command. Cancel pending
OPEN ̲LINK command. Send DISCONNECT, SRD2.
AOL11 Notify CR80 of error condition in response
to an OPEN ̲link command.
AOL12 Answer pending CR80 OPEN ̲LINK command with
error code.
Send READY FOR DISCONNECT, SRD1.
AOL13 REJECT CR80 COMMAND with REASON CODE = Current
State
AOL14 Update open ̲link ̲timeout
States entered and events occurring during a typical
OPEN LINK sequence are emphasized using fat lines in
Figure 4.2.6.1.1-1.
LTU system SW, which is used both in the X25 CSLP and
CLP is described in Reference 15.
FIGURE 4.2.6.1.1-1
STATE/EVENT TABLE: OPEN LINK SEQUENCE
4.2.6.1.2 D̲A̲T̲A̲ ̲T̲R̲A̲N̲S̲M̲I̲S̲S̲I̲O̲N̲ ̲S̲e̲q̲u̲e̲n̲c̲e̲
a) S̲t̲a̲t̲e̲s̲ ̲i̲n̲ ̲D̲A̲T̲A̲ ̲T̲R̲A̲N̲S̲M̲I̲S̲S̲I̲O̲N̲ ̲(̲S̲D̲T̲)̲
SDT0 Before for Request Input
SDT1 Request Input Received
SDT2 Subsegment receiving and accumulation
SDT3 Segment Received
SDT4 Subsegments to be Sent
SDT5 Segment Sent (but not fully acknowledged)
SDT6 Transmit Data Received
SDT7 Ready for Closing Link
b) E̲v̲e̲n̲t̲ ̲c̲l̲a̲s̲s̲e̲s̲ ̲i̲n̲ ̲D̲A̲T̲A̲ ̲T̲R̲A̲N̲S̲M̲I̲S̲S̲I̲O̲N̲ ̲(̲E̲D̲T̲)̲
EDT0 Unrecoverable Error indicated by the variable
data ̲transmission ̲error
EDT1 CR80 Close Link command
EDT2 CR80 Request Input command
EDT3 CR80 Request Output - data will have to be
sent as more than one subsegment (ETB), i.e.
data segment of more than 324 bytes.
EDT4 CR80 Request Output - data can be sent as one
subsegment (ETX), e.g. BUST's or SUPER ACK's.
EDT5 CR80 Cancel Input Request command
EDT6 CR80 Cancel Output Request command
EDT7 CR80 Show Statistics command
EDT8 CR80 Reset Statistics command
EDT9 READY FOR DISCONNECT, SDR1
EDT10 DISCONNECT, SDR2
EDT11 TRANSMIT DATA, IDR1 and subsegment ̲type:=
etb ̲subsegment
CLP has received IDR1 and remaining data to
be sent exceed 324 bytes.
EDT12 TRANSMIT DATA, IDR2 and subsegment ̲type:=
etx ̲subsegment. CLP has received IDR1 and data
to be sent can be held in one subsegment.
EDT13 CLP has received a data subsegment which is
a mid- or first subsegment of a segment, IDR3.
EDT14 CLP has received a data subsegment which is
the last subsegment or an entire segment, IDR4.
EDT15 Bits 5,4,3, OC.(5:3) is 001 (binary) corresponding
to NAK.
EDT16 Bits 5,4,3, OC.(5:3) is 001 (binary) and SC
is changed and text is present.
EDT17 Message is in error. Message checking will
be performed during analysis of input according
to Reference 18.
EDT18 Timeout. CLP has not received a response on
last message sent.
EDT19 Illegal Request output.
EDT20 Other Events.
c) A̲c̲t̲i̲o̲n̲s̲ ̲p̲e̲r̲f̲o̲r̲m̲e̲d̲ ̲d̲u̲r̲i̲n̲g̲ ̲D̲A̲T̲A̲ ̲T̲R̲A̲N̲S̲M̲I̲S̲S̲I̲O̲N̲ ̲(̲A̲D̲T̲)̲
ADT0 Prepare for input from the line. Initialize
variables.
req ̲i ̲errors:= 0
dt ̲wait ̲count:= 0
IF ack ̲to ̲be ̲sent THEN send IRD1 and
ack ̲to ̲be ̲sent:= false
ADT1 Accumulate ETB subsegment data from IDR3. Update
statistic counters. Send ACK, IRD1.
Reset counter for no response and start timer
for no response.
ADT2 Accumulate ETX subsegment data from IDR4. Send
data segment to CR80 in reply to pending Request
Input Command. Update statistic counters. Set
flag ack ̲to ̲be ̲sent:= true;
Update c ̲status entry to not received.
ADT3 Cancel pending Input Request identified in
command. Notify CR80 and clean up input buffers.
Reset c ̲status entry.
ADT4 Cancel pending Output Request identified in
command. Notify CR80 and clean up output buffers.
Reset c ̲status entry.
ADT5 Notify CR80 about the number of:
- messages transmitted
- messages retransmitted
- information messages
received error free
- messages received in error
Cf. Reference 15, section 3.1.2.
Reset c ̲status entry.
ADT6 Reset counters:
messages ̲transmitted
messages ̲retransmitted
i ̲messages ̲received
messages ̲received ̲error
Cf. Reference 15, section 3.1.2
Reset c ̲status entry.
ADT7 Reset counter for errors occurring during Request
Output.
Send BREAK, CRD2.
Clear flag ack ̲to ̲be ̲sent:= false.
Reset counter for no response and start timer
for no response.
ADT8 Update statistics. Variable request ̲o ̲errors:=
0. Send ETB ̲subsegment in IRD3.
Reset counter for no response and start timer
for no response.
ADT9 Update statistics. Variable request ̲o ̲er-
rors:= 0. Send last or entire ETX ̲subsegment
in IRD4 message. Set flag ack ̲to ̲be ̲sent: =
false.
Reset counter for no response and start timer
for no response.
ADT10 Answer pending CR80 Request Output with OK
result code upon reception of ACK on last subsegment
in segment sent. Update statistics.
Set flag ack ̲to ̲be ̲sent:= true;
Update c ̲status entry to not received.
ADT11 Update statistics. Send ACK, IRD1.
Reset counter for no response and start timer
for no response.
ADT12 Answer pending CR80. Request Output with OK
result code upon reception of ACK on last subsegment
in segment. Accumulate ETB subsegment received.
Update c ̲status entry to not received. Send
ACK no request, IRD1.
Reset counter for no response and start timer
for no response.
ADT13 Answer pending CR80 Request Output command
with OK result code upon reception of ACK on
last subsegment in segment. Send data segment
to CR80, i.e. generate OK result code to Request
Input. Set flag ack ̲to ̲be ̲sent:= true.
Update c ̲status entry to not received.
ADT14 Cancel pending CR80 commands, notify CR80 of
closing. Clean up all input/output buffers.
Send READY FOR DISCONNECT, SRD1.
Reset counter for no response and start timer
for no response.
ADT15 Cancel pending CR80 commands, notify CR80 of
closing. Clean up all input/output buffers.
ADT16 Clean up input/output buffers. Reject pending
CR80 commands with reason code = fatal error.
Reset counters: req ̲i ̲errors, req ̲o ̲errors,
data ̲transmission ̲error, and
dt ̲wait ̲count.
ADT17 Update statistics.
Increment counter for WAIT messages,
dt ̲wait ̲count, send WAIT, IRD2 with previously
used SC.
Reset counter for no response and start timer
for no response.
ADT18 IF ack ̲to ̲be ̲sent = true THEN (send IRD1 and
ack ̲to ̲be ̲sent:= false).
Reset counter for no response and start timer
for no response.
ADT19 Reject CR80 command with reason code = current
state. Reset c ̲status entry.
ADT20 Retransmit previous message with same SC and
OC.(5:3)= 001 (binary), NAK. Increment
req ̲i ̲errors, if greater than
req ̲io ̲error ̲limit, set data ̲transmission ̲error
to true. Update statistics.
Reset counter for no response and start timer
for no response.
ADT21 Retransmit previous message with same SC and
OC.(5:3)= 000 (binary), ACK.
Update statistics.
Reset counter for no response and start timer
for no response.
ADT22 Change ACK/NAK field to ACK in incoming message.
Analyze it once again, i.e. use the modified
frame as input.
ADT23 Increment req ̲i ̲errors, if then greater than
req ̲io ̲error ̲limit set data ̲transmission ̲error
to true.
ADT24 Increment req ̲o ̲errors if greater than
req ̲io ̲error ̲limit set data ̲transmission ̲error
to true.
ADT25 Send DISCONNECT to GRTS, SRD2.
ADT26 If receiving an incoming message then return.
Update the number of no response.
If number of no response is greater than
no response unit then send Disconnect and
notify CR80 of closing.
If number of no response is less than no
response unit then retransmit the previous
message with the same SC and start the
timer for no response.
If disconnect is sent then reset, state
and sequence ̲id.
Figures 4.2.6.1.2-1 and 4.2.6.1.2-2 depict typical
receive segment and send segment sequences.
Segments are received and sent by the CR80 commands
Request Input and Request Output.
The receive segment sequence emphasized in Figure 4.2.6.1.2-1
consists of:
- Request Input command
- ETB subsegment
- ETX subsegment
- Request Input command
- ETB subsegment
- ETX subsegment
- Request Input command
- TRANSMIT DATA
- Request Output command, e.g. for SUPER ACK.
A typical send segment sequence is shown in Figure
4.2.6.1.2-2. The events consist of:
- Request Output command
- TRANSMIT DATA, more than one subsegment left
to be sent
- TRANSMIT DATA, remaining data of segment is
contained in one subsegment.
- ETX subsegment (e.g. with SUPER ACK).
An overview of the most commonly used state transistions
is given in Figure 4.2.6.1.2-3.
FIGURE 4.2.6.1.2-1
STATE EVENT TABLE FOR DATA TRANSMISSION,
RECEIVE SEGMENT
FIGURE 4.2.6.1.2-2
STATE/EVENT TABLE FOR DATA TRANSMISSION,
SEND SEGMENT
FIGURE 4.2.6.1.2-3
COMMONLY USED DT STATE TRANSISTIONS
4.2.6.1.3 C̲C̲I̲S̲ ̲S̲i̲m̲u̲l̲a̲t̲i̲o̲n̲ ̲S̲e̲q̲u̲e̲n̲c̲e̲
The CCIS Simulatons is described in PC/PDS/002, Protocol
Converter: CCIS Low Level Protocol Simulator Package
Design Specification.
4.2.6.2 S̲o̲f̲t̲w̲a̲r̲e̲ ̲S̲t̲r̲u̲c̲t̲u̲r̲e̲
The CLP Package consists of the following subpackages:
a) System Software
b) CR80 Handler
c) PC Handler
d) GRTS Handler
e) V24 Line Access
f) GRTS Driver
The Line Access subpackage is responsible for handling
the V24 status line signals according to the specifications
in Reference 13.
The GRTS Driver is responsible for line communication
at the message level and generation of Block Check
Code (BCC).
Figure 4.2.6.2-1 overleaf depicts the process hierarchy
in the CLP software.
The contents of subpackages Line Access and GRTS Driver
is outlined above.
The protocol part of CLP reflects the functional description
given in section 4.2.6.1.
The Event Analyser assigns a value identifying the
event class to which an incoming event belongs. Two
sets of event classes are used depending on whether
CLP is running an OPEN LINK sequence or a DATA TRANSMISSION
sequence.
At the Protocol Entry (cf. Figure 4.2.6.2-1) the next
state entered and the action to be performed is found
from the pertinent state/event table (SOL, AOL) or
(SDT, ADT).
FIGURE 4.2.6.2-1
CLP SOFTWARE STRUCTURE
Actions identified from one of the tables are implemented
as procedures denoted open ̲link0,
open ̲link1, etc. and data ̲transmission0,
data ̲transmission1 .....
4.2.6.3 P̲a̲c̲k̲a̲g̲e̲ ̲D̲a̲t̲a̲
The data description given here is based on the syntax
for SWELL declarations even though the design is intended
for implementation in Z80 code.
CONST
req ̲io ̲error ̲limit = 10; "max err./command
dt ̲wait ̲count ̲limit= 10; "max wait counts
norespons ̲limit = 7; "max number of no response
id ̲size = 35; "char. in passwrd/id
segment ̲size = 1140; "max segment size
subsegment ̲size = 324; "max subsegm. size
TYPE
sequences = ( "const. for sequence id
open ̲link, "eol event
data ̲transmission), "edt event
cr80 ̲commands = ( "used for open, close etc.
illegal ̲command, "used if multiple commands
no ̲command, "of the same type is present
open,
close,
req ̲input,
req ̲output,
cancel ̲input,
cancel ̲output,
show ̲stat,
reset ̲stat);
command ̲state = ( "used in global table
not ̲rec, "not received
already ̲rec); "already received
pending ̲commands = "type used for check of
RECORD "CR80 commands
open ̲1,
close ̲1,
req ̲i,
req ̲o,
cancel ̲i,
cancel ̲o,
show ̲s,
reset ̲s : command ̲state;
END;
grts ̲frames =
RECORD "define message format
syn0,
syn1,
syn2,
syn3,
soh,
fc,
sc,
ac,
oc,
ic,
aux,
stx,
mc : char; "charaters
text : array(0..323) of char;
rs,
etx,
etb,
bcc : char; "charaters
END;
grts ̲messages = ( "message analysis
no ̲message, "of grts events
frame ̲error,
nak,
implied ̲ack, "text, new sc, nak
srd3, "select
srd4, "no instruction
sdr1, "RFD
sdr2, "disconnect
crd1 ̲pswrd, "logon password
crd1 ̲keywrd, "logon keyword
crd2, "break
cdr1, "line down
ird1, "ack no request
ird2, "wait
idr1, "transmit data
idr2, "DIN start
idr3, "mid subsegment
idr4, "last subsegment
seqcon); "constant sequence number
clp ̲messages = ( "msg. sent from CLP
sr1, "ready for disconnect
sr2, "disconnect
sr3, "select
sr4, "no instruction
cr1 ̲passwrd, "ID and PASSWORD
cr1 ̲keywrd, "program keyword
cr2, "break
ir1, "ACK no request
ir2, "wait
ir3, "first/mid subsegm.
ir4); "last/entire subsegm.
open ̲link ̲states = ( "constants for state id
so10, "initial state
so11, "boot load state
so12, "before SELECT
so13, "before id, passwrd
so14, "before $*$DACDINDAC
so15, "before ACK on DIN mes
so16); "closing
data ̲transmission ̲states = ("constants for state
id
sdt0, "await REQUEST INPUT
sdt1, "REQUEST INPUT received
sdt2, "subsegm. accumulation
sdt3, "segment received
sdt4, "subsegm. to be sent
sdt5, "segm. sent (not ack…08…ed)
sdt6, "TD. received
sdt7); "ready for closing link
open ̲link ̲events = ( "constants for event id
eo10, "time out or error
eo11, "OPEN LINK command
eo12, "CLOSE LINK
eo13, "RFD, SDR1
eo14, "TD, IDR1
eo15, "DIN/RST, IDR2
eo16, "simple NAK
eo17, "implied ACK
eo18, "message error
eo19, "disconnect received
eo110, "line down, CDR1
eo111); "other events
data ̲trans ̲events = ( "constants for event id
edt0, "error
edt1, "CLOSE LINK
edt2 "REQUEST INPUT
edt3, "REQUEST OUTPUT, ETB
edt4, "REQUEST OUTPUT, ETX
edt5, "CANCEL INPUT
edt6, "CANCEL OUTPUT
edt7, "SHOW STATISTICS
edt8, "RESET STATISTICS
edt9, "RFD, SDR1
edt10, "DISCON., SDR2
edt11, "TD, ETB
edt12, "TD, ETX
edt13, "ETB subsegm., IDR3
edt14, "ETX subsegm., IDR4
edt15, "simple NAK
edt16, "implied ACK
edt17, "message in error
edt18, "time out
edt 19, "illegal request output
edt20); "other events
open ̲link ̲actions = ( "action id…08…s
ao10, "init variables
ao11, "init baudrate, Send RFD,SRD1
ao12, "not used
ao13, "send SELECT, SRD3
ao14, "send CRD1, IDPSW
ao15, "send CRD1, PCTHDL
ao16, "send IRD1, ACK
ao17, "retransmit, NAK
ao18, "retransmit, ACK
ao19, "error in OPEN ̲LINK, disc.
ao110, "CLOSE LINK, disconnect
ao111, "error in OPEN ̲LINK
ao112, "send RFD
ao113, "Reject CR80 command
aol14); "update open ̲link ̲timeout
line ̲down ̲message ̲codes= ("cf Ref 18 pp 34,35
Ok, "no error.
CP, "Central system disconnects.
DIS, "Received DIS GRTS II control record.
ICC, "Invalid command to/from central system.
PAS, "Did not receive user ID password.
ABT, "No SNUMB on Abort control card.
S/I, "Missing SNUMB or IDENT card.
ONA, "Output not available.
INV, "Invalid control card.
IMF, "Invalid message format.
SLV, "Slave program not in
"system (DAC only).
OC, "Output complete.
SPD, "Link space denied.
NSA, "No link space available.
LNE, "Link number error.
6UA, "Central system unavailable.
RCE, "Retry count exhausted.
DOL, "Device off-line.
EOF, "End-of-File (EOF status cannot recover).
TNK, "Terminal not known.
RCM, "Remote computer module.
ACT, "Line active.
NDS, "Line not completely disconnected.
MCE, "Media code error.
XID, "Blank or zero ID.
"ID, "Duplicate ID.
PTF, "No PAT entries available for input.
SNB, "Messing $ SNUMB card.
SIZ, "Job source too long.
NUM, "No available program number for job.
DSC, "Excessive disk errors.
DUP, "Duplicate SNUMB's
LNK); "No disk links available.
data ̲transmission ̲actions=(
adt0, "prepare for input
adt1, "accumulate ETB subs.
adt2, "accumulate ETX subs.
adt3, "cancel INP. REQ.
adt4, "cancel OUT. REQ.
adt5, "deliver statistics
adt6, "reset statistics
adt7, "send BREAK, CRD2
adt8, "send ETB subsegm.
adt9, "send ETX subsegm.
adt10, "answer REQUEST OUTPUT
adt11, "send ACK, IRD1
adt12, "acc. ETB subsegm.
adt13, "answer REQUEST OUTPUT
adt14, "close, send RFD
adt15, "clean IO buffers
adt16, "reject CR80 comm.
adt17, "send WAIT IRD2
adt18, "send ACK if req.
adt19, "reject CR80 command
adt20, "retransmit, NAK
adt21, "retransmit, ACK
adt22, "re-analyse with ACK
adt23, "set ctrl. variables
adt24, "inc. REQ ̲O ̲ERRORS
adt25, "send DISCONNECT
adt26); "No response
subsegment ̲type = ( "ETB/ETX to be sent
etb ̲subsegment, "first/mid subsegm.
etx ̲subsegment); "last or entire
table ̲element =
RECORD
state,
action : integer;
END;
ol ̲table ̲column = "column in state event
RECORD "table for open link
s0,
s1,
s2,
s3,
s4,
s5,
s6 : table ̲element;
END;
dt ̲table ̲column =…02…"column in state event
RECORD "table for data transm.
s0,
s1,
s2,
s3,
s4,
s5,
s6,
s7 : table ̲element;
END;
clp ̲command ̲id = ( "identifies incoming cmd
clp ̲open ̲link ̲id,
clp ̲close ̲link ̲id,
clp ̲request ̲input ̲id,
clp ̲request ̲output ̲id,
clp ̲cancel ̲input ̲id,
clp ̲cancel ̲output ̲id,
clp ̲show ̲statistics ̲id,
clp ̲reset ̲statistics ̲id);
clp ̲open ̲link ̲cmd =
RECORD
command ̲id: clp ̲command ̲id;
addr: address; "pointer to parameters
END;
clp ̲logon ̲params =
RECORD
ccis ̲simulation: boolean;
baudrate ̲ccis: integer;
id ̲pass: array(0..35) of char;
END;
clp ̲close ̲cmd =
RECORD
command ̲id: clp ̲command ̲id;
END;
clp ̲request ̲input ̲cmd =
RECORD
command ̲id: clp ̲command ̲id:
addr: address; "address of data buffer
END;
clp ̲request ̲output ̲cmd =
RECORD
command ̲id: clp ̲command ̲id;
addr: address; "address of data buffer
bytes: integer;
END;
clp ̲cancel ̲input ̲cmd =
RECORD
command ̲id: clp ̲command ̲id;
END;
clp ̲cancel ̲output ̲cmd =
RECORD
command ̲id: clp ̲command ̲id:
END;
clp ̲show ̲statistics ̲cmd =
RECORD
command ̲id: clp ̲command ̲id;
addr: address; "address of clp ̲response ̲params
END;
clp ̲reset ̲statistics ̲cmd =
RECORD
command ̲id: clp ̲command ̲id;
END;
clp ̲response =
RECORD
command ̲id: clp ̲command ̲id;
result,
bytes: integer;
fill: ARRAY(0..1) OF integer;
END;
clp ̲response ̲params =
RECORD
msg ̲transmitted,
msg ̲retransmitted,
info ̲msg ̲received,
msg ̲in ̲error : integer
END;
VAR
open ̲link ̲nak ̲count, "count NAK's
event ̲class, "event recognized
state, "state id
action ̲id, "action id
req ̲o ̲errors, "count err. in DT
req ̲i ̲errors, "count err. in DT
data ̲transmission ̲error, "ctrl. variable
baudrate, "for HW initializ.
messages ̲transmitted, "statistics inform.
messages ̲retransmitted, "subsegm. retransm.
i ̲messages ̲received, "info messgs receiv.
frames ̲received ̲error, "incom. subs., error
sequence ̲id, "open, data, or ccis sim.
cr ̲80 ̲command, "of type ̲cr80 ̲commands
grts ̲message, "of type grts ̲message
out ̲byte ̲count, "bytes sent from segment
actual ̲segment ̲size, "size of segm. to be sent
message ̲reference, "pointer to msg. header
text ̲reference "pointer to text field
: integer;
start ̲protocol, "indicates RFD to be sent
open ̲link ̲timeout, "timeout flag in open link
naks ̲exceeded, "too many naks per transm.
set ̲nak, "set nak before sending
frame
freeze ̲sc, "don't change sc
ack ̲to ̲be ̲sent "flag outstanding ACK
: boolean;
id ̲pass, "for holding char. strings
test ̲id ̲pass "fixed array for simulation
: array(0..id ̲size) of char;
"35 characters & delimit.
c ̲status "table for holding status
: pending ̲commands;
grts ̲frame, "grts msg. format
clp ̲frame, "clp message format
: grts ̲frames;
message ̲status "error, nak, implied ack.
: cr80 ̲commands;
ol ̲state ̲table : array(0..eo111) OF ol ̲table ̲column;
dt ̲state ̲table : array(0..edt18) OF dt ̲table ̲column;
line ̲down ̲message ̲code: line ̲down ̲message ̲codes;
INIT "initialization of variables
id ̲pass = (:0:); "fill with nulls
test ̲id ̲pass = '$*$LOGID$PASSWORD/DNM';
ol ̲state ̲table = .......; "cf. section 4.2.6.1.1
dt ̲state ̲table = .......; "cf. section 4.2.6.1.2
ack ̲to ̲be ̲sent = true;
4.2.6.4 P̲a̲c̲k̲a̲g̲e̲ ̲D̲e̲s̲i̲g̲n̲
4.2.6.4.1 P̲r̲o̲t̲o̲c̲o̲l̲ ̲E̲n̲t̲r̲y̲ ̲P̲s̲e̲u̲d̲o̲ ̲C̲o̲d̲e̲
input :
none
output:
none
function:
the mainprogram analyzes events and acts according
to the sequence invoked (open link or data transm.)
and the current state.
the new state and next event are fetched by external
procedures.
procedures called:
event ̲analyzer
update ̲ol ̲state
update ̲dt ̲state
open ̲link0 through open ̲link14 procedures
data ̲transmission0 through data ̲transmission26
procedures
external data:
sequence ̲id
event ̲class
state
action ̲id
ol ̲state ̲table
dt ̲state ̲table
local data:
none
BEGIN "of protocol entry (CLP mainprogram)
initialize open link state event table;
initialize data transmission state event table;
initialize ccis state event table; "not implemented
sequence ̲id:= open ̲link;
state:= so10; "set initial state
REPEAT
BEGIN
event ̲analyzer(sequence ̲id) "open link or data
tr.
(event ̲class);"input found
update ̲state(state, event class) "state, event
(state, action id"new state
"and action
CASE sequence ̲id OF
open ̲link:
BEGIN
CASE action ̲id OF
ao10 : open ̲link0 () (); "cf. PDS section
ao11 : open ̲link1 () (); "4.2.6.1.1 for content
ao12 : open ̲link2 () (); "of open link
ao13 : open ̲link3 () (); "procedures
ao14 : open ̲link4 () (); "
ao15 : open ̲link5 () (); "
ao16 : open ̲link6 () (); "
ao17 : open ̲link7 () (); "
ao18 : open ̲link8 () (); "
ao19 : open ̲link9 () (); "
ao110 : open ̲link10() (); "
ao111 : open ̲link11() (); "
ao112 : open ̲link12() (); "
ao113 : open ̲link13() (); "
ao114 : open ̲link14() (); "
END; "case action ̲id in open link sequence
END; "servicing open link event
data ̲transmission:
BEGIN
CASE action ̲id OF
adt0 : data ̲transmission0 () (); "cf. PDS
sect.
adt1 : data ̲transmission1 () (); "4.2.6.1.2
for
adt2 : data ̲transmission2 () (); "content
of
"data
adt3 : data ̲transmission3 () (); "transmission
adt4 : data ̲transmission4 () (); "procedures
adt5 : data ̲transmission5 () (); "
adt6 : data ̲transmission6 () (); "
adt7 : data ̲transmission7 () (); "
adt8 : data ̲transmission8 () (); "
adt9 : data ̲transmission9 () (); "
adt10 : data ̲transmission10() (); "
adt11 : data ̲transmission11() (); "
adt12 : data ̲transmission12() (); "
adt13 : data ̲transmission13() (); "
adt14 : data ̲transmission14() (); "
adt15 : data ̲transmission15() (): "
adt16 : data ̲transmission16() (); "
adt17 : data ̲transmission17() (); "
adt18 : data ̲transmission18() (); "
adt19 : data ̲transmission19() (); "
adt20 : data ̲transmission20() (); "
adt21 : data ̲transmission21() (); "
adt22 : data ̲transmission22() (); "
adt23 : data ̲transmission23() (); "
adt24 : data ̲transmission24() (); "
adt25 : data ̲transmission25() (): "
adt26 : data ̲transmission26() (): "
END; "end data transmission actions
END; "data transmission sequence
END; "case sequence id
END until A A"forever
END; "protocol entry.
4.2.6.4.2 E̲v̲e̲n̲t̲ ̲A̲n̲a̲l̲y̲z̲e̲r̲ ̲P̲s̲e̲u̲d̲o̲ ̲C̲o̲d̲e̲
a) PROCEDURE event ̲analyzer
(sequence ̲id: sequences) "kept at return
(event ̲class: integer)
input :
sequence ̲id which type of event should be
searched for, open link, data
transmission, or ccis simulation
output :
event ̲class event class found
function:
find the event class according to the sequence
identifier entered telling which state event table
is currently used.
procedures called:
get ̲cr80 ̲command
get ̲grts ̲message
external data :
refer to the data description
local data :
none
BEGIN "procedure start
line ̲down ̲message ̲code:= OK; "initialize result code
IF sequence ̲id = open ̲link THEN
BEGIN
event ̲class:= eo111;
IF open ̲link ̲timeout = true LOGOR
naks ̲exceeded = true THEN
event ̲class:= eo10
ELSE
BEGIN "message decoding
get ̲grts ̲message()(grts ̲message);
IF grts ̲message NE no ̲message THEN
BEGIN
CASE grts ̲message OF
frame ̲error : event ̲class:= eo18;
nak : event ̲class:= eo16;
implied ̲ack : event ̲class:= eo17;
sdr1 : event ̲class:= eo13;
sdr2 : event ̲class:= eol9;
cdr1 : event ̲class:= eo110;
idr1 : event ̲class:= eo14;
idr2 : event ̲class:= eo15;
OTHERWISE event ̲class:= eo111;
END; "end case clause
ELSE
BEGIN "get ̲cr80 ̲command
get ̲cr80 ̲command() (cr80 ̲command)
IF cr80 ̲command NE no ̲command THEN
BEGIN
CASE cr80 ̲command OF
open : event ̲class:= eo11;
close : event ̲class:= eo12;
OTHERWISE event ̲class:= eo111; "illegal
com
END "end case clause
END; "end get cr80 message
END; "end message decoding
IF sequence ̲id = data ̲transmission THEN
BEGIN
event ̲class:= edt18; "other events are edt18
IF data ̲transmission ̲error = true THEN
event ̲class:= edt0
ELSE
BEGIN
gets ̲grts ̲message()(grts ̲message);
IF grts ̲message NE no ̲message THEN
BEGIN
CASE grts ̲message OF
frame ̲error : event ̲class:= edt17;
nak : event ̲class:= edt15;
implied ̲ack : event ̲class:= edt16;
sdr1 : event ̲class:= edt9;
sdr2 : event ̲class:= edt10;
idr1 :
BEGIN "ETX or ETB to be sent?
IF actual ̲segment ̲size - out ̲byte ̲count
is less than or equal to subsegment ̲size
THEN
event ̲class:= edt12
ELSE
event ̲class:= edt11;
END; "end of idr1 analysis
idr3 : event ̲class:= edt13;
idr4 : event ̲class:= edt14;
OTHERWISE event ̲class:= edt18;
END
ELSE
event ̲class:= edt18; "no message from grts
ELSE
BEGIN "there was no new GRTS command
get ̲grts ̲message()(grts ̲message);
BEGIN
get ̲cr80 ̲command()(cr80 ̲command);
IF cr80 ̲command NE no ̲command THEN
BEGIN "new cr80 command has arrived
CASE cr80 ̲command OF
close : event ̲class:= edt1;
req ̲input : event ̲class:= edt2;
req ̲output :
BEGIN
IF actual ̲segment ̲size is less than or
equal to subsegment ̲size THEN
event ̲class:= edt4
ELSE
event ̲class:= edt3;
END; "req output with ETX or ETB segment
cancel ̲input : event ̲class:= edt5;
cancel ̲output : event ̲class:= edt6;
show ̲stat : event ̲class:= edt7;
reset ̲stat : event ̲class:= edt8;
OTHERWISE event ̲class:= edt18;
END "end of cr80 command case clause
END; "grts message analysis
END; " event is not data transm. error
END; " sequence ̲id is data ̲transmission
END; " procedure event ̲analyser
b) PROCEDURE get ̲cr80 ̲command
() "no input
(cr80 ̲command: cr80 ̲commands);
input :
none
output :
cr80 ̲command identified by constant contained
in the type declaration cr80 ̲commands
function:
check for presence of a cr80 ̲command. Check
to avoid multiple pending commands of the
same type
procedures called:
cr80 communication module
external data :
command ̲status: table with one entry for each
possible cr80 command. Entries have values
not ̲rec or already ̲rec "received or not
local data:
temp ̲state: command ̲state "for local use
BEGIN "of procedure get ̲cr80 ̲command
cr80 ̲command:= no ̲command; "output if no comm.
call cr80 communication module
IF cr80 ̲command is present THEN
cr80 ̲command:= constant; "constant of type
"cr80 ̲commands
temp ̲state:= not ̲rec;
CASE cr80 ̲command OF "see if already pending
no ̲command: ; "no action
open: temp ̲state:= c ̲status.open ̲1;
close: temp ̲state:= c ̲status.close ̲1;
req ̲input: temp ̲state:= c ̲status.req ̲i;
req ̲output: temp ̲state:= c ̲status.req ̲o;
cancel ̲input: temp ̲state:= c ̲status.cancel ̲i;
cancel ̲output: temp ̲state:= c ̲status.cancel ̲o;
show ̲stat: temp ̲state:= c ̲status,show ̲s;
reset ̲stat: temp ̲state:=c ̲status.reset ̲s;
OTHERWISE ; "no action
IF temp ̲state = already ̲rec THEN
BEGIN
cancel the command received (clear RAM area
of the excessive command)
CASE cr80 ̲command OF "restore table entry
no ̲command: ; "no action
open: c ̲status.open ̲1:= not ̲rec;
close: c ̲status.close ̲1:=not ̲rec; req
̲input:
c
̲status.req
̲i:=
not
̲rec;
req ̲output: c ̲status.req ̲o:= not ̲rec;
cancel ̲input: c ̲status.cancel ̲i:= not ̲rec;
cancal ̲output: c ̲status.cancel ̲o:= not ̲rec;
show ̲stat: c ̲status.show ̲s:= not ̲rec;
reset ̲state: c ̲status.reset ̲s:= not ̲rec;
OTHERWISE : "no action
cr80 ̲command:= illegal ̲command;
END
ELSE
BEGIN "normal update of command status
CASE cr80 ̲command OF "restore table entry
no ̲command: ; "no action
open: c ̲status.open ̲1:= already ̲rec;
close: c ̲status.close ̲1:= already ̲rec;
req ̲input: c ̲status.req ̲i:= already ̲rec;
req ̲output: c ̲status.req ̲o:= already ̲rec;
cancel ̲input: c ̲status.cancel ̲i:= already ̲rec;
cancel ̲output: c ̲status.cancel ̲o:= already rec;
show ̲stat: c ̲status.show ̲s:= already ̲rec;
reset ̲stat: c ̲status.reset ̲s:= already ̲rec;
OTHERWISE ; "no action
END; "end of normal table update
END; "end procedure get ̲cr80 ̲command
c) PROCEDURE get ̲grts ̲message
( ) "no input
(grts ̲message : grts ̲messages)
input :
none
output :
constant identifying grts message event
(no ̲message, nak, or regular messages).
Refer to Package Data, section 4.2.6.3
function:
see if a grts message has arrived.
Return with message- or error identification
or the value no ̲message.
procedures called:
check ̲grts ̲buffer
external data:
none
local data:
message ̲group : integer of TYPE =(service,
control, info);
fc ̲code, oc ̲code : integer;
BEGIN "of get ̲grts ̲message
"check for incoming message"
check ̲grts ̲buffer() (message ̲status,
message ̲reference,
text ̲reference);
grts ̲message:= message ̲status;
IF LOGAND
grts ̲message NE frame ̲error LOGAND
grts ̲message NE nak LOGAND
grts ̲message NE implied ̲ack LOGAND
grts ̲message NE seqcon THEN
BEGIN "ordinary message
fc ̲code:= grts ̲frame.fc; "get function code
oc ̲code:= grts ̲frame.oc; "get operation code
IF fc ̲code = #42 LOGOR
fc ̲code = #43 THEN
message ̲group:= service;
IF fc ̲code = #44 THEN message ̲group:= control;
IF fc ̲code = #4D THEN message ̲group:= info;
grts ̲message:= frame ̲error;
CASE message ̲group OF
service:
BEGIN "service message validation
IF oc ̲code = #44 THEN
grts ̲message:= sdr1; "RFD
IF oc ̲code = #46 THEN
grts ̲message:= sdr2; "disconnect
IF oc ̲code = #42 THEN
grts ̲message:= srd3; "select
IF oc ̲code = #40 THEN
grts ̲message:= srd4; "no instruction
END; "service message validation
control:
BEGIN "ctrl. msg. validation
IF oc ̲code NE #40 LOGOR
(grts ̲frame.sc NE #41 LOGAND "cf.Ref. 18,p33
grts ̲frame.sc NE #42) LOGOR
grts ̲frame.stx NE #02 LOGOR
(grts ̲frame.mc NE #48 LOGAND
grts ̲frame.mc NE #4E) LOGOR
grts ̲frame.rs NE #1E THEN
grts ̲message:= frame ̲error;
IF grts ̲frame.text = …08…$*$LOGID$PSWRD/DNM…08… THEN
grts ̲message:= crd1 ̲pswrd; "simulation
IF grts ̲frame.text = …08…$*$DACDINDAC…08… THEN
grts ̲message:= crd1 ̲keywrd; "simulation
IF grts ̲frame.text = #31 THEN
grts ̲message:= crd2; "break
IF grts ̲frame.text = …08…LINE DISCONNECTED XXX…08…
LOGOR
grts ̲frame.text = …08…LINE TERMINATED XXX…08…
THEN
BEGIN "line down control message received
grts ̲message:= cdr1; "line down message
look up the constant of type
line ̲down ̲message ̲codes corresponding
to the string XXX. Store the
constant in the variable
line ̲down ̲message ̲code.
END;
END; "ctrl message validation
info:
BEGIN
IF (oc ̲code NE #40 LOGAND "validation
oc ̲code NE #42 LOGAND "Ref.18,p33
oc ̲code NE #44) LOGOR
(grts ̲frame.sc NE #41 LOGAND
grts ̲frame.sc NE #42) LOGOR
grts ̲frame.stx NE #02 LOGOR
(grts ̲frame.etb NE #03 LOGAND
grts ̲frame.etx NE #17) THEN
grts ̲message:= frame ̲error;
ELSE
BEGIN " valid message
IF oc ̲code = #40 THEN
grts ̲message:= idr2; "transmit data
IF oc ̲code = #42 THEN
BEGIN "no request message
IF grts ̲frame.text = …08……08… THEN "no text
grts ̲message:= ird1; "ack no request
IF oc ̲code = #44 THEN
IF grts ̲frame.text = …08…(*)DINDAC…08… LOGOR
grts ̲frame.text = …08…(*)RSTRT…08… THEN
grts ̲message:= idr2; "DIN/RST msg.
IF grts ̲message NE idr2 LOGAND
grts ̲frame.text NE …08……08… THEN
BEGIN
IF grts ̲frame.etb = #17 THEN
grts ̲message:= idr3; "etb subsegm.
IF grts ̲frame.etx = #03 THEN
grts ̲message:= idr4; "etx subsegm.
END;
END; "no request message
END; "valid message
END; "information message
END; "end case message group
END; "end of normal message validation
END; "procedure get ̲grts ̲message
d) PROCEDURE check ̲grts ̲buffer
()
(message ̲status : grts ̲messages,
message ̲reference,
text ̲reference : integer)
input :
none
output :
message ̲status which holds a constant from the
constants listed in …08…grts ̲messages…08…, i.e.
no ̲message, frame ̲error, nak, implied ̲ack
function:
check incoming message buffer for the arrival
of a message
procedures called:
TBD during coding phase
external data:
grts ̲frame: grts ̲frames; "cf. Package Data
local ̲data:
fc ̲code, oc ̲code, old ̲sc, new ̲sc : integer;
parity ̲ok, block ̲check ̲ok : boolean;
BEGIN
message ̲status:= no ̲message;
check for incoming message in buffer
IF no message present THEN
message ̲status:= no ̲message
ELSE
BEGIN "grts message is present
check for odd parity computed by HW (bit 4 of
…08…read…08… register #1 on LTU SIO circuit)
IF no parity error THEN
parity ̲ok:= true
ELSE
parity ̲ok:= false;
compute a vertical ex ̲OR on characters following
SOH (#01) and including ETX(#03) or ETB(#17)
IF grts ̲frame.bcc = BCC computed THEN
block ̲check ̲ok:= true
ELSE
block ̲check ̲ok:= false;
fc ̲code:= grts ̲frame.fc; "check function code
IF (fc ̲code NE #42 LOGAND
fc ̲code NE #43 LOGAND "used in SELECT
fc ̲code NE #44 LOGAND
fc ̲code NE #4D) LOGOR
parity ̲ok = false LOGOR
block ̲check ̲ok = false THEN
message ̲status:= frame ̲error
ELSE
BEGIN "check for nak and implied ack
message ̲reference:= ADDRESS(grts ̲frame); "pointer
text ̲reference:= ADDRESS(grts ̲frame.text);
new ̲sc:= grts ̲frame.sc; "sequence code
message ̲status:= idr3; "arbitrary NE nak
oc ̲code:= grts ̲frame.oc;
IF oc ̲code.(5:3) = 001 (binary) THEN
BEGIN
message ̲status:= nak;
IF new ̲sc NE old ̲sc LOGAND
grts ̲frame.text NE …08……08…THEN "text is present
message ̲status:= implied ̲ack;
END "oc ̲code investigation
ELSE
BEGIN
IF old ̲sc = new ̲sc
then message ̲status = seqcon,
END;
END; "implied ack and nak check
END; "grts message present
old ̲sc:= new ̲sc;
END; "procedure
e) PROCEDURE update ̲state
(state, event ̲class) "input
(state, action ̲id) "output
input :
current state to be updated
event class identified in procedure event ̲analyzer
output :
new state
action identifier
function:
update state and find action ̲id from
ol ̲state ̲table or dt ̲state ̲table
external data:
ol ̲state ̲table, dt ̲state ̲table
BEGIN
Case sequence ̲id of
open ̲link:
BEGIN "update ̲ol ̲state
(state, action ̲id):= ol ̲state ̲table(state,
event ̲class);
END; "end procedure
data ̲transmission:
BEGIN "update ̲dt ̲state
(state, action ̲id):= dt ̲state ̲table(state,
event ̲class);
END; "end procedure update ̲dt ̲state
END "case sequence ̲id
END;
4.2.6.4.3 S̲e̲n̲d̲ ̲C̲L̲P̲ ̲M̲e̲s̲s̲a̲g̲e̲ ̲P̲s̲e̲u̲d̲o̲ ̲C̲o̲d̲e̲
PROCEDURE send ̲clp ̲message
(clp ̲message: clp ̲messages,
set ̲nak,
freeze ̲sc: boolean)
( )
input :
constant of type clp ̲messages (see section
4.2.6.3) identifying which message is to
be sent. Userid and password are given
in global variables userid and passwrd.
set ̲nak = true causes nak field to be set
freeze ̲sc = true will cause the sc field
to remain constant compared to previous
message sent from CLP
output :
none
function:
send a particular message to grts according
to the message identification held in the
variable clp ̲message.
set sequence code field and nak field according to
input booleans
procedures called:
link driver module
external data:
clp ̲message: clp ̲messages; "constant
clp ̲frame: grts ̲frames; "format of message
set ̲nak, freeze ̲sc: boolean;
local data:
old ̲sc: integer; "previous SC
"used by PC
BEGIN "procedure send ̲clp ̲message
CASE clp ̲message OF
sr1 : prepare ready for disconnect, SRD1
sr2 : prepare disconnect, SRD2
sr3 : prepare select, SRD3
sr4 : prepare no instruction, SRD4
cr1 ̲passwrd: prepare userid, password, CRD1
cr1 ̲keywrd: prepare program keyword, CRD1
cr2 : prepare break, CRD2
ir1 : prepare ack no request, IRD1
ir2 : prepare wait, IRD2
ir3 : prepare first, mid subsegm., IRD3
ir4 : prepare last/entire subsegment, IRD4
tcrd1 : prepare line down ctrl. msg., TCRD1
tird1 : prepare transmit data, TIRD1
tird2 : prepare DINDAC start msg., TIRD2
OTHERWISE ; " end case
IF set ̲nak = true THEN
clp ̲frame.oc(5:3):= 001 (binary);
IF freeze ̲sc = false THEN
BEGIN
IF old ̲sc = #41 THEN
clp ̲frame.sc:= #42
ELSE
clp ̲frame.sc:= #41;
END
ELSE
clp ̲frame.sc:= old ̲sc; "previous sc from CLP side
send message prepared in buffer clp ̲frame
END; "procedure send ̲clp ̲message
4.2.6.5 P̲a̲c̲k̲a̲g̲e̲ ̲I̲n̲t̲e̲r̲f̲a̲c̲e̲s̲
CLP receives the following commands from CPA:
- logon
- close link
- request input
- request output
- cancel input request
- cancel output request
CLP receives the following commands from CI:
- show statistics
- reset statistics
All commands are issued to CLP through the LTU driver
which passes command records to the LTU.
Generally, commands consist of records. In each record
the first item is an integer identifying the command.
This command identification is followed by one or more
parameters. The format of a Request Output command
is shown below.
TYPE
clp ̲request ̲output ̲cmd =
RECORD
command ̲id: clp ̲command ̲id;
addr: address; "integer pointer to output buffer
bytes: integer;
END;
The type clp ̲command ̲id consists of simple integer
constants.
Similarly responses are communicated to CR80 using
formats such as
TYPE
clp ̲request ̲output ̲rsp =
RECORD
command ̲id: clp ̲command ̲id;
result: integer;
... "additional
... "parameters
END;
A complete description of command formats is given
in section 4.2.6.3.
A detailed description of formats and command response
diagrams is given in PC/AUX/009: Protocol Converter
CR80 - LTU I/F
