GE PACSystems RX7i - Page 218

Chapter 6. Serial I/O, SNP & RTU Protocols
GFK-2222AD April 2018 207
Example COMMREQ Data Block for Configuring Serial I/O Protocol
Values
Meaning
Address
12
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
5 = Serial I/O
Protocol
Address + 8
not used
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, 2 = Software
Flow Control
Address + 12
not used
Turnaround Delay
Address + 13
not used
Timeout
Address + 14
0=7 bits, 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
0 = 2-wire, 1 = 4-wire, 2 = 4-wire transmitter always on
Duplex Mode