Estun ETS-101010APC-CAN - Chapter 6; MODBUS Communication; Communication Wiring

ETS Series AC Servo User's Manual
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Chapter 6
MODBUS Communication
6.1 RS-485 Communication Wiring
ETS series servo drives provide the MODBUS communication function with RS-485 interface,
which can be used to easily set parameters or to perform monitoring operations and so on.
The definitions of the servo drive communication connector terminals(CN3、CN4) are as follows.
Terminal No.
Name
Function
1
—
Reserved
2
—
Reserved
3
485+
RS-485 communication terminal
4
ISO_GND
Isolated ground
5
ISO_GND
6
485-
RS-485 communication terminal
7
CANH
CAN communication terminal
8
CANL
CAN communication terminal
Note：
1. The length of the cable should be less than 100 meters and in a environment with minimal electrical
disturbance/interference. However, if the transmission speed is above 9600bps, please use the communication cable
within 15 meters to ensure transmission accuracy..
2. A maximum of 31 servo drives can be connected when RS485 is used. Terminating resistances are used at both ends
of the 485 network. If more devices are wanted to connect, use the repeaters to expand.
3. CN3 of servo drive is always used as communication cable input terminal，and CN4 is always used as communication
cable output terminal(If still need to connect slave stations，the communication cable is connected from CN4 terminal to
the next slave station; if need not, add balance resistor in CN4 terminal.).It is prohibited to connect CN3 of any two servo
drives directly when multiple ETS series servo drives are connected.
Example:
When a RS-485 network is composed of a PLC and three servo drives (A, B, and C), the cable wiring is shown as follows:
PLC→CN3 of A, CN4 of A→CN3 of B, CN4 of B→CN3 of C, CN4 of C→120Ω terminating resistance.