Yaskawa iQpump Drive User Manual User Manual
Page 211
D.1 Using Modbus Communication
YASKAWA
TM.iQp.01 iQpump Drive User Manual
211
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Message Format
In Modbus communication, the master sends commands to the slave, and the slave responds. The message format is configured for both
sending and receiving as shown below. The length of the data packets is changed by the command (function) contents.
Figure D.4 Message Format
The space between messages must support the following:
Figure D.5 Message Spacing
Slave Address
Set the iQpump drive address from 0 to 32. If 0 is selected, commands from the master will be broadcast (i.e., the iQpump drive will not
return responses).
Function Code
The function code specifies commands. There are four function codes, as shown below.
Table D.3 Function Codes
Data
Configure consecutive data by combining the storage register address (test code for a loopback address) and the data the register contains.
The data length changes depending on the command details.
Error Check
Errors are detected during communication using CRC-16. Perform calculations using the following method:
1. The factory setting for CRC-16 communication is typically zero, but when using the Modbus system, set the factory setting to one
(e.g., set all 16 bits to 1).
2. Calculate CRC-16 using MSB as slave address LSB, and LSB as the MSB of the final data.
3. Calculate CRC-16 for response messages from the slaves and compare them to the CRC-16 in the response messages.
Slave address
Function code
Data
Error check
Function Code
(Hexadecimal)
Function
Command Message
Response Message
Min. (Bytes)
Max. (Bytes) Min.* (Bytes)
Max. (Bytes)
03H
Reading/Holding Register Contents
8
8
7
37
06H
Write In Single Holding Register
8
8
8
8
08H
Loopback Test
8
8
8
8
10H
Write In Several Holding Registers
11
41
8
8
* Minimum bytes for a normal Response Message (error response message is always 5 bytes).
DDC to Drive
Drive to DDC
DDC to Drive
Command message
Response message
Command message
Time (Seconds)
24 bits long
5 ms min.
H5-06
setting
24 bits long