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21-MAR-2007
MAN0847-01
No part of this publication may be reproduced without the prior agreement and written permission of Horner APG, Inc.
Information in this document is subject to change without notice.
.
For RS484 cabling, it is suggested that 24 AWG twisted pair copper wire with 16pF/ft capacitance be
used. Maximum cable length is determined by the combination of cable length (in meters) and data
signaling rate (in bps).
RS-485 allows multiple devices (up to 32) to communicate at half-duplex on a single pair of wires, plus a
ground wire, at distances up to 1200 meters (4000 feet). Both the length of the network and the number
of nodes can easily be extended using a variety of repeater products on the market. Data is transmitted
differentially on two wires twisted together, referred to as a "twisted pair."
CSCAPE configuration
To enable an OCS device for use with the HE500232485 converter, an Open function block must be
provided that configures the associated OCS port for
Multidrop Half
handshaking. This configuration
allows the OCS to drive the HE500232485 converter’s CTS (transmit enable) handshake line for
transmitting data.
HE500RS232485 DB9P Pin configuration
DB9P Pin
RS-232 Function
Direction
1
Data carrier detect (DCD)
In *
2
Transmit data (TxD)
Out
3
Receive data (RxD)
In
4
Data terminal ready (DTR)
Out *
5 Ground
(Gnd) —
6 Unused __
7
Ready to send (RTS)
Out *
8
Clear to send (CTS)
(Turns Transmit On)
In
9 Unused __
1
9
DB9P
Connector
* Pins 1, 4, 7 Tied Together Internally, and Not Required for Normal
Operation
