Rs-232 control protocol, Overview, Command string structure – Contemporary Research ICE-HE User Manual

Page 12: Command format

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Contemporary Research

12

ICE-HE Ethernet Head End

Overview

RS-232 control for up to 4000 iC-Net devices is provided through an iC series Head-End Network

Controller. The ICC-HE Head-End manages iC-Net communication over RF Coax to ICC-series devices

as well as ICW-series devices over twisted-pair Cat3/5 wiring. The ICW-HE Head-End operates on the

Cat5 network only.

Each device is assigned a unique device number from 1 to 4000 to which control commands are

addressed. The devices are organized into 16 zones of 255 devices. All the devices in each zone will

respond to a single ―virtual device number‖ — one device number that represents all devices in each

zone. There is also a global device number, 4095, that will command all devices in the system. This

feature dramatically speeds up system operation and programming, because one command can affect

an entire group of devices—or all. To take advantages of this feature, review the section iC-Net Zones

in this manual.

In ABC-Net Media Retrieval Systems, we reserve the first group of devices, 1-255, for components

operating on a connected control system. Zones 1-16 are used for CR TV Controllers, Video Display

Controllers and Tuners. As it‘s unlikely any system will use all 4000 devices, this may be a good device

standard for your system as well.

The Remote RS-232 port on the Head-End Network Controller can communicate from 1200 to 38.4K

baud. The factory default setting is 19.2K baud, 8 data bits, No parity, and 1 stop bit.


Command String Structure

Characters in command strings are expressed in

a combination of hex and ASCII characters.

Single-byte hex numbers are preceded

by the „$‟ symbol

ASCII characters or strings are

enclosed in single quotes

Numbers not marked as hex or ASCII

are a single decimal byte

Parameters shown in < > brackets are

single byte

A series of multiple commands or

parameters are set apart by [ ]

brackets

Commas separate the bytes, but are
not part of the protocol

Double quotes enclose the command

string, but are not part of the protocol

Command format

“$A5,<dh>,<dl>,<ncb>,<cmd1>,<parameter> [<cmdN>]"

$A5

Starts the command

<dh>

The zone or high order byte of the device

<dl>

The unit or low order byte of the device (0

for global zone)

<ncb>

The number of command bytes to follow

<cmd1>

The first command byte

<parameter> Command parameters (not used by all

commands)

[<cmdN>]

Multiple commands can be concatenated,

with byte count added to <ncb>


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