Chapter 6. Serial I/O, SNP & RTU Protocols
206
PACSystems* RX7i, RX3i and RSTi-EP CPU Reference Manual
GFK-2222AD
Example COMMREQ Data Block for Configuring RTU Protocol
Values
Meaning
Address
13, or 17
Data Block Length
A 1
0 = No Wait (WAIT mode not supported)
WAIT/NOWAIT Flag
A 2
0008 = %R, register memory
Status Word Pointer Memory Type
A 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
A 4
not used
Idle Timeout Value
A 5
not used
Maximum Communication Time
A 6
FFF0H
Command Word (serial port setup)
A 7
3 = RTU
Protocol
A 8
0 = Slave
Port Mode
A 9
COMMREQ Command Block Parameter Values
Data Rate
A 10
0 = None, 1 = Odd, 2 = Even
Parity
A 11
0 = Hardware, 1 = None
Flow Control
A 12
not used
Turnaround delay
A 13
not used
Timeout
A 14
not used (RTU always chooses 8 bits by default)
Bits per Character
A 15
not used (RTU always chooses 1 stop bit by default)
Stop Bits
A 16
not used
Interface
A 17
0 = 2-wire, 1 = 4-wire, 2 = 4-wire transmitter always on
Duplex Mode
A 18
Station Address (1-247)
Device Identifier
A 19
Count of 100 µs units (0 = 3.5 character times)
End-of-frame timeout
83
A 20
not used
A 21
not used
A 22
Count of 10 ms units (range 0-255)
Receive-to-transmit delay
83
83
The End-of-frame timeout and Receive-to-transmit delay values were added in Release 6.70 for the RX3i. They are discussed
in the
section.
