Read Port Status Function (4303) - GE VersaMax PLC User Manual

Serial I/O / SNP / RTU Protocols
For public disclosure
12.4.6.1 Example Command Block for the Flush Input Buffer
Function
VALUE
(decimal)
address 0001
address +1 0000
address +2 0008
address +3 0000
address +4 0000
address +5 0000
address +6 4302

12.4.7 Read Port Status Function (4303)

This function returns the current status of the port. The following events can be detected:
• A read request was initiated previously and the required number of characters has
now been received or the specified time-out has elapsed.
• A write request was initiated previously and transmission of the specified number of
characters is complete or a time-out has elapsed.
The status returned by the function indicates the event or events that have completed.
More than one condition can occur simultaneously, if both a read and a write were
initiated previously.
12.4.7.1 Example Command Block for the Read Port Status
Function
VALUE
(decimal)
address 0003
address +1 0000
address +2 0008
address +3 0000
address +4 0000
address +5 0000
address +6 4303
address +7 0076
address +8 0101
VALUE
(hexadeci-
mal)
Data block length
0001
0000 NOWAIT mode
Status word memory type (%R)
0008
Status word address minus 1 (%
0000
R0001)
0000 Not used
0000 Not used
Flush input buffer command
10CE
VALUE
(hexadecimal)
Data block length
0003
0000 NOWAIT mode
Status word memory type (%R)
0008
Status word address minus 1 (%
0000
R0001)
0000 Not used
0000 Not used
Read port status command
10CF
Port status memory type (%M)
004C
Port status memory offset (%M101)
065
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