Moxa Technologies Industio C114HI, Manual

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Chapter 9 RS-232/422/485 Programming
The C114HI could be used for RS-232, RS-422 or RS-485 communications. It comes
with a high level RS-232 Application Programming Library, API-232, for serial
communication control under DOS, Windows 3.x, Windows NT and Windows 95.
With proper jumper settings and cable wiring, users can program as follows :
9.1 RS-232 Programming
Please refer to the API-232 User's Manual or the documentation file \API-232.TXT
in the API-232 or Windows NT/95 driver diskette.
9.2 RS-422 Programming
When RS-422 is needed, there is no difference from RS-232 in programming except
that the jumper settings must be "Tx ON" and "Rx ON".
9.3 RS-485 Programming
The C114HI has four independent ports and each port has one receiver and one
transmitter. Both of the transmitter and receiver can be either enabled or disabled in
order to achieve not only point-to-point communication but also the multidrop
communication.
Depending on the jumper settings described in Section 2.2, there are three ways for
controlling transmitter and receiver of the port.
1. RTS ON/OFF
When the RTS signal is true, the transmitter is enabled and the receiver is
disabled. Otherwise, the transmitter is in the high impedance status and can not
transmit any signal.
A statement of as following will set RTS signal true and turn on the transmitter: