YASKAWA GA800

6.3 MEMOBUS/Modbus Communications
320 YASKAWA SIEPC71061737D GA800 Drive Technical Reference
◆ Examples of Messages for Commands/Responses
The items in this section are examples of messages for commands/responses.
■ Read Multiple Holding Registers
Uses function code 03 (Hex.) to read the contents of a maximum of 16 holding registers.
Table 6.7 shows example messages when the drive reads status signal from the drive of slave 2, the error contents,
fault contents, and frequency references.
Table 6.7 Message Example When Reading the Contents of Holding Register
Byte Command Message
Setting Data
(Hex.)
Response Message (Normal)
Setting Data
(Hex.)
Response Message (Fault)
Setting Data
(Hex.)
0 Slave address 02 Slave address 02 Slave address 02
1 Function code 03 Function code 03 Function code 83
2
Starting No.
Upper 00 Data Qty 08 Error code 03
3 Lower 20
First storage
register
Upper 00
CRC-16
Upper F1
4
Data Qty
Upper 00 Lower 65 Lower 31
5 Lower 04
Next storage
register
Upper 00 -
6
CRC-16
Upper 45 Lower 00 -
7 Lower F0
Next storage
register
Upper 00 -
8 - Lower 00 -
9 -
Next storage
register
Upper 01 -
10 - Lower F4 -
11 -
CRC-16
Upper AF -
12 - Lower 82 -
■ Loopback Test
The loopback test uses function code 08 (Hex.) and returns the command message as a response message. This test
checks communication between the master and slave. The test code and data can use desired values.
Table 6.8 shows examples of messages given out when the loopback test is done with the drive of slave 1.
Table 6.8 Message Examples from the Loopback Test
Byte Command Message
Setting Data (Hex.)
Response Message (Normal)
Setting Data (Hex.)
0 Slave address 01 Slave address 01
1 Function code 08 Function code 08
2
Test code
Upper 00
Test code
Upper 00
3 Lower 00 Lower 00
4
Data
Upper A5
Data
Upper A5
5 Lower 37 Lower 37
6
CRC-16
Upper DA
CRC-16
Upper DA
7 Lower 8D Lower 8D
■ Writing to Multiple Holding Registers
You can write the data that you set to the number of holding registers set in function code 10 (hex). You must
configure the number of the holding registers and each 8 higher bits and 8 lower bits in order in the command
message for the write data. You can write to a maximum of 16 holding registers.
Table 6.9 shows example messages when you use the PLC to set Forward run in the drive of slave 1 with a 60.00 Hz
frequency reference.