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3 device definition, 4 automatic configuration, 5 port definitions – Kramer Electronics VS-4228 User Manual

Page 10: On 3.2.4

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VS-4228 - Overview

7

A master device always transmits over pins 3 and 8 and receives over 2 and 7.

A slave device always transmits over pins 2 and 7 and receives over 3 and 8.

The communication path must be kept clear between the master and slave units in

both directions, since the slave device must respond to any command transmitted

by the master. If the master receives no response from the slave, the master

cancels the communication with the slave machine and sometimes flags a

message: no communication.

For example, in video production when a special controller (with play and rewind

functionality) is the master device, each command transmitted to the slave device

must reach that slave device and that slave device must respond, otherwise the

master device disconnects.

3.2.3

Device Definition

In many broadcast applications, different machines involved in production can be

either slaves or masters. Using a device as a master means that the device talks

via pins 3 and 8 and listens via pins 2 and 7. In another setup, that uses the same

device as a slave, this means that the device talks via pins 2 and 7 and listens via

pins 3 and 8.

For example, an edit controller always works as a master. During an editing

session, a VTR may be the slave to the edit controller. However, in a duplication

setup, the VTR may become a master for a second VTR.

3.2.4

Automatic Configuration

After connecting the 9-pin D-sub connectors and cables between the controlled

units, the VS-4228 automatically configures which pins to use in the 9-pin D-sub

connector according to the assignment of each machine.

3.2.5

Port Definitions

Modern equipment usually has only one connector, RS-422, which functions as a

master as well as a slave.