96
8 Communications protocol
8.1 Application Scope
Applicable series: EA100
Applicable network: Support Modbus protocol, RTU format, RS485 bus.
The typical RTU message frame format:
Start Bit
Device Address
Function Code
Data
CRC
Stop Bit
T1-T2-T3-T4
8Bit
8Bit
n*8Bit
16Bit
T1-T2-T3-T4
8.2 Physical interface
RS485 asynchronous half duplex communication mode
RS485 terminal default data format
：
1-8-N-1, baud rate
：
9600bps
Data format: 1-8-N-1/2, 1-8-O-1/2, 1-8-E-1/2, baud rate 4800bps, 9600bps, 19200bps, 38400bps, 57600bps optional, can be set by the
function code P7-01 and P7-02
8.3 Protocol format
CRC Parity
Initial Block of
Frame
≥
Idle
Periods of 4 Bits
Address of
Slave
Command
Code
Data
Stop Block of
Frame
≥
Idle
Periods of 4 Bits
ADU
Figure 1 protocol format
The parity in ADU (Application Data Unit) is obtained via the CRC16 parity of the 1
st
three parts of ADU and switching the low bytes and high
bytes. Low bytes of CRC parity go first, and high bytes of it follow in the protocol format.
8.4 Command interpretation
Command code 0x03: Read parameter and status of servo drive.
ADU Item
Byte No.
Range
Master requests:
Address of slave
1
0
-
0FEH
Command code
1
0x03
Register start address
2
0x0000
-
0x0FFFF
Register number
2
0x0000
-
0x0008
CRC parity(Low bytes go first)
2
Slave responds
：
Address of slave
1
Servo drive address
Command code
1
0x03
Byte length
1
2* Register number
Register data
2* Register number
CRC parity
2
Command code 0x06: write servo drive single function code or control parameters
ADU Item
Byte No.
Range
Master requests:
Address of slave
1
0
-
0FEH
Command code
1
0x06
Byte length
2
0x0000
-
0x0FFFF
Register data
2
0x0000
-
0x0FFFF
CRC parity
2
Slave responds
：
Address of slave
1
Local address
Command code
1
0x06
Read bytes
2
0x0000
-
0x0FFFF
Register data
2
0x0000
-
0x0FFFF
CRC parity
2
Command code 0x10: rewrite the servo drive multiple function code or control parameters
ADU Item
Byte No.
Range
Host send request
：
Address of slave
1
0
-
0FEH
Command code
1
0x10
Register start address
2
0x0000
-
0x0FFFF
Register number
2
0x0000
-
0x0008
Byte length of register data
1
2* Register number
Register data
2* Register number
