5. LADDER COMMUNICATION
IM9000F02-E2
41
5.1.5 Reversal of read/write data bytes
There are two methods of sending word data : One is to send the data from the upper byte and the
other is to send the data from the lower byte.
The following two items can be inverted : Identifier (ID) and data (DAT).
Only the data (DAT) can also be inverted by setting.
Number of bytes
1
1
2
2
2
1
1
Number of BCD
digits
2
2
4
4
4
2
2
Details
STX
(02H)
Device
addres
s
(ADR)
Identifie
r
(ID)
Command
(CMD)
Data
(DAT)
CR
(0DH)
LF
(0AH)
These two items can be inverted
.
Inverting method
Reversal of Identifier (ID) and data (DAT)
The usual data transfer order is reversed by the command (CMD).
PLC
o
REX-F9000 (During data send from PLC)
Command
(CMD)
Details
Identifier transfer order
(0000)
0001
Read request
Upper byte
o
Lower byte
0010
Write request, write data + (Positive)
0011
Write request, write data - (Negative)
0100
Read request (Byte inversion)
1000
Write request, write data + (Positive)
Lower byte
o
Upper byte
1100
Write request, write data - (Negative)
Other
Usage inhibited
Continued on the next page.
