6-100
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.
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 60.0 Hz in the slave 1 Inverter by the PLC.
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
place
00H
Test Code
Higher
place
00H Error Code 01H
Lower
place
00H
Lower
place
00H
CRC-16
Higher
place
86H
Data
Higher
place
A5H
Data
Higher
place
A5H
Lower
place
50H
Lower
place
37H
Lower
place
37H
CRC-16
Higher
place
DAH
CRC-16
Higher
place
DAH
Lower
place
8DH
Lower
place
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
place
00H
Start
Address
Higher
place
00H Error code 02H
Lower
place
01H
Lower
place
01H
CRC-16
Higher
place
CDH
Quantity
Higher
place
00H
Quantity
Higher
place
00H
Lower
place
C1H
Lower
place
02H
Lower
place
02H
No. of data 04H
CRC-16
Higher
place
10H
Lead data
Higher
place
00H
Lower
place
08H
Lower
place
01H
Next data
Higher
place
02H
Lower
place
58H
CRC-16
Higher
place
63H
Lower
place
39H
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