10
Rev. 1.0
11/08/2017
STF-R/C Hardware Manual
400-820-9661
RS-485 network connection
Multiple –R model drive network can be built via dual RS-485 communication port by network
cable provided.
RS-485 Four-wire Configuration
RS-485 four-wire system utilize separate transmit and receive wires. One pair of wires connect
the host’s transmit signals(TX+/TX-) to each drive’s RX+/RX- receive terminals. The other pair
connects the drive’s TX+/TX- terminals to the host’s receive signals. A logical ground terminal is
provided on each drive and can be used to keep all the drives at the same ground potential. The
rst drive’s logical GND of the RS-485 bus must connect to host’s ground.
Four-wire Connection
Connect the drive’s RX+ to the TX+ terminal of the host controller,and connect the drive’s RX- to
the TX- terminal of the host controller . Connect the drive’s TX+ to the RX+ terminal of the host
controller,and connect the drive’s TX- to the RX- terminal of the host controller .
Connect the drive’s GND and the host’s GND to a same ground.
NOTE: The RS-485 port on the drive is isolated from internal circuitry of the drive. So the
GND of each drive’s RS-485 port must be connected together. The rst drive’s GND of the
RS-485 port must be connected to the GND of RS-485 port on the host PC or controller.
RS-485 Tow-wire Configuration
In a two-wire system ,the data transmitting and receiving use a same cable. the host must stop
its transmitting before receiving data. That means the host must stop transmit data before drive
begins to answer a query which just come from the host, otherwise the host cannot receive
any data witch sent from a drive. There is a transmit delay parameter that can be adjusted to
compensate for a host that is slow to disable its transmitter. This adjustment can be set over the
network using the TD command,it also can be set by using the STF Congurator software. Users
can set a shorter transmit delay in a four-wire system.
Two-wire connection
The RX+ and TX+ of the drive connect to the host’s + in parallel. The RX- and TX- of the drive
connect to the host’s - in parallel. Connect the drive’s GND and the host’s GND to a same ground.
NOTE: The RS-485 port on the drive is isolated from internal circuitry of the drive. So the
GND of each drive’s RS-485 port must be connected together. The rst drive’s GND of the
RS-485 port must be connected to the GND of RS-485 port on the host PC or controller.
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