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STAC6 Hardware manual
920-0029 Rev. B
11/19/2010
STAC6 drives include 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 STAC Configurator™ software. It is not necessary to set the transmit delay in a four wire
system. We recommend a 120 ohm terminating resistor be connected between the two transmit / receive
wires at the farthest drive from the host.
RS-232 to RS-485 2-wire Converter
Model 485-25E from Integrity Instruments (800-450-2001) works 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’s TX+
and RX+ terminals. Connect “A” to the drive’s TX- and RX- terminals.
Converting USB to RS-485
The USB-COMi-M from www.byterunner.com is an excellent choice for USB to RS-485 conversion. It can be
used with 2 wire or 4 wire systems.
For two wire RS-485, set SW1 to ON and SW2-4 to OFF. On the USB-COMi-M screw terminal connector:
Pin1 goes to RX- and TX-.
Connect pin 2 to RX+ and TX+.
Pin 6 is ground.
The DB-9 is not used.
For four wire RS-485, set SW1,3,4 to ON and SW2 to OFF. On the USB-COMi-M screw terminal connector:
USB-COMi-M STAC6 Drive
pin 1 RX-
pin 2 RX+
pin 3 TX+
pin 4 TX-
pin 6 GND
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