GE VersaMax PLC

12.2.4.1 Example
1. Port 1 is running RTU Slave protocol at 9600 baud.
2. A programmer is attached to port 1. The programmer is using 9600 baud.
3. The CPU installs SNP Slave on port 1 and the programmer communicates normally.
4. The programmer stores a new configuration to port 1. The new configuration sets the
port for SNP Slave at 4800 baud (it will not take effect until the port loses
communications with the programmer).
5. When the CPU loses communications with the programmer, the new configuration
takes effect.
12.2.5 Example COMMREQ Command Block for
Configuring SNP Protocol
Values
Meaning
Address 10H
Data Block Length
Address + 1 0 = No Wait
WAIT/NOWAIT Flag
Address + 2
0008 = %R, register memory
Status Word Pointer Memory
Type
Address + 3
Zero-based number that gives the address of
the COMMREQ status word (for example, a
value of 99 gives an address of 100 for the
status word)
Status Word Pointer Offset
Address + 4
0 (Only used in Wait/No Wait mode)
Idle Timeout Value
Address + 5
0 (Only used in Wait/No Wait mode)
Maximum Communication Time
Address + 6 FFF0H
Command Word (serial port
setup)
Address + 7 0001 Protocol: 1=SNP
Address + 8 0000=Slave Port Mode
Address + 9
7=38400, 6=19200, 5=9600, 4=4800
Data Rate
Address + 10
0 = None, 1 = Odd, 2 = Even
Parity
Address + 11 1 = None Flow Control
Address + 12
0 = None, 1 = 10ms, 2 = 100ms, 3 = 500ms
Turnaround Delay
Address + 13
0 = Long, 1 = Medium, 2 = Short, 3 = None
Timeout
Address + 14 1 = 8 bits Bits Per Character
Address + 15
0 = 1 Stop Bit, 1 = 2 Stop bits Stop Bits
Address + 16 not used Interface
Address + 17 not used
Duplex Mode
Address + 18
user-provided
†
Device identifier bytes 1 and 2
Address + 19
user-provided
†
Device identifier bytes 3 and 4
Address + 20
user-provided
†
Device identifier bytes 5 and 6
230 GFK-1503E VersaMax PLC User Manual
For public disclosure