Yaskawa P7 Drive User Manual - Manual (Page 222)

Communications D - 8
Loopback Test (08H)
The loopback test returns the command message directly as the response message without changing the contents to check the
communications between the master and slave. Set user-defined test code and data values.
The following table shows a message example when performing a loopback test with the slave 1 Drive.
Fig. D.8 Function Code 08H Message Example
Write In Several Holding Registers (10H)
Write the specified data to the registers from the specified addresses. The written data must be consecutive, starting from the
specified address in the command message: Higher 8 bits, then lower 8 bits, in storage register address order.
The following table shows an example of a message when a forward run command has been set at a speed command of
60.0 Hz in the slave 1 Drive by the PLC.
Fig. D.9 Function Code 10H Message Example
Command Message
Response Message
(During Normal Operation)
Response Message
(During Error)
Slave address 01H Slave address 01H Slave address 01H
Function code 08H Function code 08H Function code 89H
Test Code
Higher 00H
Test Code
Higher 00H Error Code 01H
Lower 00H Lower 00H
CRC-16
Higher 86H
Data
Higher A5H
Data
Higher A5H Lower 50H
Lower 37H Lower 37H
CRC-16
Higher DAH
CRC-16
Higher DAH
Lower 8DH Lower 8DH
Command Message
Response Message
(During Normal Operation)
Response Message
(During Error)
Slave Address 01H Slave Address 01H Slave Address 01H
Function Code 10H Function Code 10H Function Code 90H
Start
Address
Higher 00H Start
Address
Higher 00H Error code 02H
Lower 01H Lower 01H
CRC-16
Higher CDH
Quantity
Higher 00H
Quantity
Higher 00H Lower C1H
Lower 02H Lower 02H
No. of data 04H
CRC-16
Higher 10H
Lead data
Higher 00H Lower 08H
Lower 01H
Next data
Higher 02H
Lower 58H * No. of data = 2 x (quantity)
CRC-16
Higher 63H
Lower 39H
IMPORTANT
Set the number of data specified using command messages as quantity of specified messages x 2. Handle
response messages in the same way.