YASKAWA Varispeed G7 Series Instruction Manual page 332

Loopback Test
The loopback test returns command messages directly as response messages without changing the contents to
check the communications between the master and slave. You can set user-defined test code and data values.
The following table shows a message example when performing a loopback test with the slave 1 Inverter.
Command Message
Slave address
Function code
Test Code
Data
CRC-16
Writing to Multiple Storage Registers
Write the specified data to each specified storage register from the specified addresses. The written data must
be in the following order in the command message: Higher place 8 bits, then lower place 8 bits, in storage reg-
ister address order.
The following table shows an example of a message when forward operation has been set at a frequency refer-
ence of 60.00 Hz in the slave 1 Inverter by the PLC.
Command Message
Slave Address
Function Code
Higher
place
Start
Address
Lower
place
Higher
place
Quantity
Lower
place
No. of data
Higher
place
Lead data
Lower
place
Higher
place
Next data
Lower
place
Higher
place
CRC-16
Lower
place
01H
08H
Higher
00H
place
Lower
00H
place
Higher
A5H
place
Lower
37H
place
Higher
DAH
place
Lower
8DH
place
Response Message
(During Normal Operation)
01H Slave Address
10H Function Code
Higher
00H
place
Start
Address
Lower
01H
place
Higher
00H
place
Quantity
Lower
02H
place
Higher
04H
place
CRC-16
Lower
00H
place
01H
02H
58H
63H
39H
Response Message
Slave address 01H
Function code 08H
Higher
00H
place
Test Code
Lower
00H
place
Higher
A5H
place
Data
Lower
37H
place
Higher
DAH
place
CRC-16
Lower
8DH
place
Response Message
01H Slave Address
10H Function Code
00H Error code
01H
CRC-16
00H
02H
10H
08H
Individual Functions
(During Error)
01H
90H
02H
Higher
CDH
place
Lower
C1H
place
99
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