Appendix A. Remote Control; Introduction; Eia-485 - Comtech EF Data MBT-5003 Installation And Operation Manual

L-band up/down converter system

Table of Contents

A.1

This appendix describes the protocol and message command set for remote monitor and control of the MBT-5003 L-Band Up/Down

Converter System.

The electrical interface is an EIA-485 multi-drop bus for the control of many devices, 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.

The Remote Control connector pinout is shown in Chapter 3.2.6 COM (EIA-485 Interface), J3 (DB-9F).

NOTE

A.2

For applications where multiple devices are to be monitored and controlled, a full-duplex (4-wire plus ground) EIA-485 is preferred. Half-

duplex (2-wire plus ground) EIA-485 is possible, but is not preferred. In full-duplex EIA-485 communication, there are two separate,

isolated, independent, differential-mode twisted pairs, each handling serial data in different directions.

It is assumed that a 'Controller' device (a PC or dumb terminal) transmits data in a broadcast mode via one of the pairs. Many 'Target'

devices are connected to this pair, and all simultaneously receive data from the Controller. The Controller is the only device with a line-

driver connected to this pair; the Target devices have only line-receivers connected.

Appendix A. REMOTE CONTROL

A–1

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