Veichi AC310 Service Manual page 43

Input
TXD1
side
A+
Output
B-
side
3. Implementation method and key device selection
2. Type of fault
Abnormal communication, communication failure reported
3. Inspection Methods
Method 1: Communicate directly with 485 through the serial port of the computer, and
check whether the communication is good or not.
Method 2: Or use two AC drives to communicate, use oscilloscope to measure the port
voltage (differential signal) according to the voltage difference between AB to judge whether
there is any abnormality.
Concrete way:
⚫ Build two sets of AC300CON-A1.0 platforms
⚫ A+ connected to A+, B- connected to B-
TXD1 signal from CPU
TXD1 Differential signal A+ processed by SP485EEN-L
TXD1 Differential signal B- after SP485EEN-L processing
Voltage difference between
transmitter AB:
+2V ~ +6V: Logic positive
level voltage
-2V ~ -6V: Logic negative
level voltage Voltage
difference between receiver
AB:
>+200mv: Logic positive
level voltage
<-200mv: Logic negative
level voltage
AC310 Universal AC Drive Service Manual
42