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4–9
This section provides guidelines for selecting the modems you use with the
1785-KE in point-to-point applications using full-duplex protocol.
The modem you use to interface to an Allen-Bradley RS-232-C
communication module (using full-duplex protocol) must be capable of:
supporting the standard RS-232-C handshaking described in
Appendix B
supporting the baud rate of your module
operating on a full-duplex link
interfacing to an asynchronous device
operating in a “transparent” mode (data is passed over the link without
being modified)
Note: If handshaking is enabled (via the SW-1 switch selection discussed
in Chapter 3), and the DCD signal is lost for more than approximately
10 seconds, the 1785-KE follows the handshaking sequence described in
the section “Using the 1785-KE in an Auto-Answer Application” later in
this chapter. If your modem does not support this sequence, you can either
disable handshaking, or with handshaking enabled, jumper DTR to DSR at
the module to insure the module will recover after DCD is restored.
The 1785-KE can communicate via modems over either a:
dedicated link (such as a leased phone line)
dial-up link
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