3.2 Protocol Functions
3-9
3
MELSEC Commands Supported by the 218IF
The following table shows the common MELSEC ACPU commands supported by the
MP900-Series 218IF Module, and the MEMOBUS command codes corresponding to these
commands.
Note: Special AnACPU commands are not supported. Use the common
ACPU commands for AnACPU access. AnACPU expansion registers
cannot be accessed.
Communications Programs
MELSEC protocol communications can be performed by user programs using the MSG-
SND and MSG-RCV functions.
Refer to Appendix A System Functions for information on using the MSG-SND and MSG-
RCV functions.
The MELSEC protocol functions supported by the 217IF and the 218IF differ.
Table 3.4 Common MELSEC ACPU Commands
Extended
MEMOBUS
Command
MELSEC
Command
Description Qty Remarks
01H/02H 00H Reads bit devices in 1-point units 256 points
−
− 01H Reads bit devices in 16-point units 128 words
(2,048 points)
Not supported
03H/04H
09H/0AH
Reads word devices in 1-point units 256 points
−
05H/0FH 02H Writes bit devices in 1-point units 256 points
−
− 03H Writes bit devices in 16-point units 40 words (640 points)
Not supported
06H/00BH
10H
Writes word devices in 1-point units 256 points
−
− 05H Randomly specifies, sets, and resets
bit devices and device numbers in
16-point units
40 words (640 points)
Not supported
0EH Randomly specifies, sets, and resets
word devices and device numbers in
1-point units
40 points
−
08H 16H Loopback test 256 bytes
−
31H 60H Fixed buffer communications 507 words
−
32H 61H Reads random access buffer commu-
nications
508 words
−
33H 62H Writes random access buffer com-
munications
508 words
−
INFO
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