Yaskawa MP920 Communications Module - Manual (Page 38)

3 Communications Protocols
3.2.2 MEMOBUS Protocol
3-6
„ General-purpose Message Mode
The contents of Controller’s holding registers (MW registers) can be transmitted or received
in the general-purpose message mode.
As shown in the following diagram, the specified length of data starting from the specified
address in consecutive holding registers in the Controller is transmitted without processing.
The Controller does not wait for a response.
The data size that can be handled in one communication is from 1 word to 510 words.
3.2.2 MEMOBUS Protocol
„ Overview
The MEMOBUS Protocol is the standard protocol that has been used up to now for Yaskawa
RS-232C communications, and it is the main communications protocol for Yaskawa Control-
lers.
Fig. 3.2 MEMOBUS Message Flow in Communications
Between Controller and Personal Computer
Controller’s holding registers
MW
Y
MSG-SND function parameters
No.
05
06
I/O
IN
IN
Contents
Data address
Data size
CPU
MSG-RCV
217IF/218IF
CPU
MSG-SND
217IF
Controller
MOMOBUS messages
Controller