Memobus Protocol - YASKAWA MP3000 Series User Manual
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2.16 Details on Protocols
MEMOBUS Protocol
MEMOBUS Protocol
Message Structure
The following message structure is used in communications with 217IF and 218IF Modules. Refer to the
following manual for details.
MEMOBUS Descriptive Information Industrial Communication System (Manual No. SIE-C815-13.60)
When the MEMOBUS protocol is used to send and receive data, each message consists of two fields: a
header field and the application data field. The 218 header that is used for the Extended MEMOBUS pro-
tocol is not used.
The header is for TCP/IP and UDP/IP connections and is used only for Ethernet communications. User
programs do not need to be aware of this header because it is automatically appended and removed in the
218IFD.
When communicating using the 217IF, only the MEMOBUS application data field is sent and received.
The structure for parameters in the application data field is given below. The actual data for the MEMO-
BUS protocol is stored in the application data field.
Communications Protocol
MEMOBUS message communications
MEMOBUS message communications
Note
2-402
Header
Whether RTU or ASCII is used for Ethernet communications depends on the code setting for the
remote station in the connection parameters. When communicating with a 217IF Module, this is deter-
mined by the communications mode setting in the communications parameters.
When a message is received in Ethernet communications, neither the CRC-16 in RTU Mode nor the
LRC in ASCII Mode are checked. Error checking for received messages is performed using error
detection in the TCP, UDP, and IP headers. It is therefore not necessary to calculate the CRC-16 or
LRC when sending a message.
MEMOBUS application data
MEMOBUS Message
Application will use only
this field.
TCP/IP header
(only for Ethernet
communications)
Code
RTU
MEMOBUS RTU Mode (page 2-404)
ASCII
MEMOBUS ASCII Mode (page 2-409)
Reference
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