Emerson PACSystems RX3i - Example COMMREQ Data Block for Configuring RTU Protocol

PACSystems™ RX3i and RSTi-EP CPU Reference Manual Section 6
GFK-2222AK October 2019
Serial I/O, SNP & RTU Protocols 139
6.1.8 Example COMMREQ Data Block for Configuring RTU
Protocol
Values
Meaning
Address
13, or 17
Data Block Length
Address + 1
0 = No Wait (WAIT mode not supported)
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
not used
Idle Timeout Value
Address + 5
not used
Maximum Communication Time
Address + 6
FFF0H
Command Word (serial port
setup)
Address + 7
3 = RTU
Protocol
Address + 8
0 = Slave
Port Mode
Address + 9
See COMMREQ Command Block Parameter Values.
Data Rate
Address + 10
0 = None, 1 = Odd, 2 = Even
Parity
Address + 11
0 = Hardware, 1 = None
Flow Control
Address + 12
not used
Turnaround delay
Address + 13
not used
Timeout
Address + 14
not used (RTU always chooses 8 bits by default)
Bits per Character
Address + 15
not used (RTU always chooses 1 stop bit by default)
Stop Bits
Address + 16
not used
Interface
Address + 17
0 = 2-wire, 1 = 4-wire, 2 = 4-wire transmitter always on
Duplex Mode
Address + 18
Station Address (1-247)
Device Identifier