Hitachi NES1-004SB Quick Reference Manual page 167

(E) Loopback Test [08h]
This function checks a master-slave transmission using any test data. An example follows:
 Send test data to an inverter having slave address "1" and receiving the test data from the
inverter (as a loopback test).
Query:
No. Field Name
1 Slave address *1
2 Function code
3 Test subcode
(high order)
4 Test subcode
(low order)
5 Data (high order)
6 Data (low order)
7 CRC-16 (high order)
8 CRC-16 (low order)
Broadcasting is disabled.
Note 1:
When test subcode is for echo (00h, 00h) only and not available to the other commands.
Chapter 8 Communication Functions
Response:
Example
No.
(Hex)
01 1 Slave address *1
08 2 Function code
00 3 Test subcode
(high order)
00 4 Test subcode
(low order)
Any 5 Data (high order)
Any 6 Data (low order)
CRC 7 CRC-16 (high order)
CRC 8 CRC-16 (low order)
8 - 13
Example
Field Name
(Hex)
01
08
00
00
Any
Any
CRC
CRC