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Video Recorder - User Manual 33
2.5.7.4 Connecting the RS422/485 link to a computer
The VRX180 video recorder with the RS422/485 Communications option can be connected your
computer using one of two arrangements :
• Wired to an RS422/485 compatible serial port (if the computer is equipped with such a port).
• Wire the RS232 serial port of the computer to an RS232 to RS485 converter. The RS485 port
of the converter should be wired to the Communications port of the VRX recorder.
Arrangement
ICS plug-in I/O board
Description
Wired directly to the RS422/485 port in your computer using an ICS plug-
in I/O board which is specifically designed to interface with the IBM (or
IBM compatible) PC, PC/XT; or PC/AT computer.
This board is available from...
ICS Computer Products, Inc.
5466 Complex Street
Suite 208
San Diego, California 92123
Burr-Brown Converter Using the RS232 port a Burr-Brown RS232 to RS422/485 converter
installed between the RS232 port and the video recorder.
This converter is available from :
Burr-Brown
International Airport Industrial Park
P.O. Box 11400
Tucson, Arizona 85734
Part number LDM485ST, limited distance modem
Westermo converter The Westermo MA44 converts RS232 to RS422/485. It is installed
between the RS232 port and the video recorder.
2.5.7.5 Rear connection
The video recorder has built in circuits to reduce the effects of most electrical noise. We recommend
that you review the following guidelines, to minimize the noise effects.
1. Separate the communication leadwires from the line voltage, the alarm output, contactors, motors etc...
2. For a communication distance, over 1.5 meters, use a separate metal tray, or metal conduit.
3. Use wiring cable composed of twisted pair wirings, with a shield for RS485 and RS422. Use a shielded
cable for RS232.
4. Connect the shield wire to the ground, at one end only, preferably at the video recorder. Use for example
a wiring cable type: Belden 9271 twinax, or equivalent.
5. We recommend to install a 120 ohms resistor between TXA and TXB, on the last video recorder on
communication link.
6. The maximum capabilities are:
Type of communication Distances max. # of Unit
RS232 15 meters / 50 feet 1
RS422 1000 meters / 3280 feet 15
RS485 1200 meters / 4000 feet 31