PACSystemsâ„¢ 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
0 = No Wait (WAIT mode not supported)
0008 = %R, register memory
Status Word Pointer Memory
Type
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
Maximum Communication Time
Command Word (serial port
setup)
See COMMREQ Command Block Parameter Values.
0 = None, 1 = Odd, 2 = Even
not used (RTU always chooses 8 bits by default)
not used (RTU always chooses 1 stop bit by default)
0 = 2-wire, 1 = 4-wire, 2 = 4-wire transmitter always on