Two-wire configuration, Assigning rs-485 addresses, 18 stm23 hardware manual – Applied Motion STM23C-3CE User Manual
Page 18
Two-Wire Configuration
RS-422/485 Connector diagram
Transmit and receive on the same pair of wires can lead to trouble. The host must not only disable its transmitter before
it can receive data, it must do so quickly, before a drive begins to answer a query. The STM23 includes a “transmit delay”
parameter that can be adjusted to compensate for a host that is slow to disable its transmitter. This adjustment can be
made over the network using the TD command, or it can be set using the
ST Configurator
software. It is not necessary to
set the transmit delay in a four-wire system.
NOTE: a 120 ohm terminating resistor is required at the end of a two wire network.
RS-232 to RS-485 2-wire Converter
Model 485-25E frorks well for converting your PC’s RS-232 port to RS-485.
It comes with everything you need. Connect the adaptor’s “B” pin to the Drive+Motor’s TX+ and RX+ terminals. Connect
“A” to the drive’s TX- and RX- terminals.
Assigning RS-485 Addresses
Before wiring the entire system, you’ll need to connect each drive individually to the host computer so that a unique
address can be assigned to each drive. Use the
ST Configurator™
software, available at Applied Motion’s website for this
purpose.
Connect the drive to your PC and then launch the
ST Configurator™
software. Finally, apply power to your drive. If you
have already configured your drive, then you should click the Upload button so that the
ST Configurator™
settings match
those of your drive. Click on the Motion button, then select the SCL operating mode. If you have a Q drive, you may
want to select “Q Programming”. Either way, you’ll see the RS-485 Address panel appear. Just click on the address charac-
ter of your choice. You can use the numerals 0..9 or the special characters ! “ # $ % & ‘ ( ) * + , - . / : ; < = > ? @ . Just make
Typical RS-422/485 Two-Wire System
+Rx- +Tx- GND
+Rx- +Tx- GND
+Rx- +Tx- GND
to Host Tx+ (B)
to Host Tx- (A)
to Host GND
Drive 1
Drive 2
Drive n
120
GND
TX–
TX+
RX–
RX+
18
STM23 Hardware Manual
920-0021F
2/14/2012