YASKAWA MP920 User Manual page 40

3 Communications Protocols
3.2.3 MELSEC-A Protocol
MEMOBUS
Command
01H/02H
03H/04H
0FH
10H
08H
MP900-Series Controller
CPU
MSG-SND MSG-RCV
217IF/
218IF
Fig. 3.3 MELSEC Format Message Flow
Between a Controller and MELSEC-A
MELSEC Commands Supported by the 217IF
The following table shows the common MELSEC ACPU commands supported by the
MP900-Series 217IF Module, and the MEMOBUS command codes corresponding to these
commands.
Table 3.3 Common MELSEC ACPU Commands
MELSEC
Command
WR Reads bit devices in 16-point units
Reads word devices in 1-point units
WW Writes bit devices in 16-point units
Writes word devices in 1-point units
TT Loopback test
Note: Special AnACPU commands are not supported. Use the common
ACPU commands for AnACPU access. AnACPU expansion registers
cannot be accessed.
MELSEC format
Description
32 words (512 points)
64 points
10 words (160 points)
64 points
254 characters
3-8
MELSEC-A
Ethernet
Qty Remarks
−
−
−
−
−