User manual

Computer Gateway User Manual 4-2 5/96
4.1.1
Table 4-2 shows the set of startup messages, while Figure 4-1 illustrates a simple
startup-message sequence including components at the communications level. Details
of the initialization messages are found at paragraph 4.3.
• Normal Operation-message sequences are initiated by the host processor, each with a
required CG response message. These request-response pairings are shown in Table
4-3, and an example of a normal operation-message exchange, including components at
the communications level, is shown in Figure 4-2.
Table 4-1 — Communications Handler Level Messages
MESSAGE TYPE TRANSACTION SENT NOTES
CODE BY
Time Synch 31 CG Requires host to echo back same
message
Confirmation 30 either Required response to any applications-
level message. Negative confirmation
requires sender to retransmit the
message.
Link Fail 32 either Used to initiate failover from dual-link
to single-link operation
Table 4-2 — Applications Level Messages During Initialization or Restart
MESSAGE TYPE TRANSACTION SENT REQUIRED RESPONSE
CODE BY
CG Restore 43 CG Zero or more of the following
request types followed by Restore
Complete (44)
DB List Request 47/147 Host Database List Response (48/148)
ACIDP Prog Mode Chg 22/122 Host Program Mode Change Response
(23)
ACIDP Exec State Chg 21/121 Host none
Store Internal DDT in CG 10 Host Store Internal DDT response (12)
Delete Internal DDT from CG 11 Host Delete Internal DDT response (12)
Internal DDT Con/Discon 45/145 Host Connect/Disconnect response
(46/146)
Restore Complete 44 Host none