YASKAWA GA800 Technical Reference page 318

6.3 MEMOBUS/Modbus Communications
■
Slave Address
Set the slave address of the drive to 00 to FF (Hex.). When the slave address is 00 (Hex), the master sends the
command and all slaves receive the command.
The slave will not send a response message to the master.
■
Function Code
There are five function codes that set commands.
Function Code Subfunction Code
(Hex.) (Hex.)
03
08
10
5A
010D
67
010E
■
Communications Data
Communications data is a series of data that uses the combination of the communications register number and the data
for these registers. The data length changes when the description of the command changes. For a loopback test, it
switches to test code.
The communications register for the drive has a 2-byte length. Data that is written to the register for the drive is
usually 2 bytes. Register data that is read from the drive is also 2 bytes.
■
Error Check
Error check uses the CRC-16 method to detect transmission errors. Use the procedure in this section to calculate
CRC-16.
Command Data
When the drive receives data, it will make sure that there are no errors in the data. The drive uses the procedure below
to calculate CRC-16, then the drive compares that data with the CRC-16 value in the message. If the CRC-16 values
do not agree, the drive will not execute a command message.
When you calculate CRC-16 in MEMOBUS/Modbus communications, make sure that you set the start value as FFFF
(Hex.). All 16 bits must be 1.
318
Figure 6.7 Message Format
Table 6.5
Table 6.5 Function Codes
Function
Read Multiple Holding
-
Registers
- Loopback Test
Writing to Multiple
-
Holding Registers
Writing to Multiple
Holding Registers /
-
Reading the Register
Indicated
Reading the Contents of
Non-Consecutive
Holding Registers
Writing to Non-
Consecutive Holding
Registers
shows the different codes.
Command Message
Minimum Data Maximum Data
Length Length
(byte) (byte)
8 8
8 8
11 41
11 41
10 248
14 250
YASKAWA SIEPC71061737D GA800 Drive Technical Reference
Response Message
Minimum Data Maximum Data
Length Length
(byte) (byte)
7 37
8 8
8 8
17 17
10 248
8 8