Overlapping Commreqs - GE PACSystems RX7i Reference Manual

6.2.5 Overlapping COMMREQs

Some Serial I/O COMMREQs must complete execution before another COMMREQ can be processed.
Others can be left pending while others are executed.
COMMREQS that Must Complete Execution
■ Autodial (4400)
■
Initialize Port (4300)
■
Set Up Input Buffer (4301)
■ Flush Input buffer (4302)
■
Read port status (4303)
■ Write port control (4304)
■
Cancel Operation (4399)
■
Serial Port Setup (FFF0)
COMMREQs that can be Pending While Others Execute
The table below shows whether Write Bytes, Read Bytes and Read String COMMREQs can be pending
when other COMMREQs are executed.
Currently-Pending
COMMREQs
Write Bytes
No
(4401)
Read Bytes
No
(4402)
Read String
No
(4403)
GFK-2222AD
No Yes Yes Yes
Yes Yes No No
Yes Yes No No
April 2018
Chapter 6. Serial I/O, SNP & RTU Protocols
NEW COMMREQ
Yes Yes Yes
Yes Yes No
Yes Yes No
Yes Yes No
No Yes No
No Yes No
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