Protocol Functions; Extended Memobus Protocol - YASKAWA MP920 User Manual

3 Communications Protocols

3.2.1 Extended MEMOBUS Protocol

3.2

Protocol Functions

3.2.1

Extended MEMOBUS Protocol

The Extended MEMOBUS protocol is used between Controllers with the 218IF Module. It
can also be used between 215IF Modules.
From a functional point of view, Extended MEMOBUS provides extended functions over the
MEMOBUS protocol using conventional RS-232C communications. A wider range of func-
tions and more efficient communications are provided than with the MEMOBUS protocol.
The MEMOBUS mode and the general-purpose message mode are available with the
Extended MEMOBUS protocol. These are specified in the parameters of the send message
and receive message functions (MSG-SND and MSG-RCV).
Extended MEMOBUS Protocol Functions
The functions provided by the Extended MEMOBUS protocol are shown in the following
table.
Table 3.2 Extended MEMOBUS Protocol Functions
Function
Code
01H Coil status read
02H Input relay status read
03H Holding register write
04H Input register write
05H Single coil status change
06H Single holding register write
08H Loopback
09H
Holding register read (extended)
0AH
Input register read (extended)
0BH Holding register write (extended)
0DH Discontinuous multiple holding register read (no
header)
0EH Discontinuous multiple holding register write
0FH Multiple coil status change
10H Multiple register write
31H MELSEC fixed buffer communications
32H MELSEC random buffer read
33H MELSEC random buffer write
Function
3-4
No. of Points Remarks
−
2,000 points
−
2,000 points
−
125 words
−
125 words
−
1 point
−
1 word
− −
−
508 words
−
508 words
−
507 words
−
508 words
−
254 words
−
800 points
−
100 words
218IF only
507 words
218IF only
508 words
218IF only
507 words