Individual Functions
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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 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 regis-
ter 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
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.