Omron SYSDRIVE 3G3MV A2002, User Manual

Page: 204 / 348

7-10
7-2 Message Communications Basic Formats
The following description provides information on the format of message
data (DSR and response data).
Message communications of the Inverter conform to the MODBUS Com-
munications Protocol, which does not require message start and end pro-
cessing.
(The MODBUS Communications Protocol is a trademark of AEG
Schneider Automation.)
H
Communications Format
·
The following format is used for message data communications.
·
Message data consists of a Slave address, function code, communications data, and
error check block.
Message data (DSR
message and response)
Slave address
1 byte
Function code
1 byte
Communications
data
Error check
block
2 bytes
H
Message Interval
·
When the Inverter receives a DSR message from the Master, the Inverter waits for a
period that is equivalent to 24 bits in length and a Send Wait Time set in n156. Then the
Inverter will return a response. Set n156 according to the Master’s processing time or
the timing adjustment.
·
When the Master issues the next message after receiving the response from the
Inverter, the Master must wait for a 24-bit period plus another period of at least 10 ms.
DSR message from Master
Response from Inverter
DSR message from Master
24-bit (or 3-byte)
standby period
Standby period
set in n156
24-bit (3-byte)
standby period
Set a standby period of
10 ms or more for the
Master.
Communications Chapter 7