Appendix A. Remote Control; Table A-1. Eia-485 Interface - Comtech EF Data CSAT-5060 Installation And Operation Manual

Appendix A. REMOTE CONTROL

A.1 I
NTRODUCTION
This document describes the protocol and message repertoire for remote monitor and control of
the CSAT Outdoor terminal.
The electrical interface is either an EIA-485 multi-drop bus (for the control of many devices) or
an EIA-232 connection (for the control of a single device), and data is transmitted in
asynchronous serial form, using ASCII characters. Control and status information is transmitted
in packets, of variable length, in accordance with the structure and protocol defined in later
sections.
A.1.1 EIA-485
The EIA-485 interface is provided at the 19-pin circular J5 connector. The interface is a 4-wire
EIA-485 interface using the pin out shown in the table below. Since a half-duplex
communication protocol is used, the +Tx and +Rx as well as the –Tx and –Rx signals can be tied
together at the user end to support a 2-wire interface. The EIA-485 driver is only active during
transmission and is tri-stated when not is use.

Table A-1. EIA-485 Interface

Pin Signal Name I/O
A EIA--485 +Rx Input
B EIA--485 –Rx Input
C EIA--485 +Tx Output
D EIA--485 –Tx Output
T Ground Passive
Notes
CSAT Receive line
CSAT Receive line complement
CSAT Transmit line
CSAT Transmit line complement
A-1