Overview
3
Figure 1: Bi-directional Signals I
When a Master device changes position with a Slave device, the pins
automatically change, as section 3.1.6 describes and as Figure 2 illustrates:
Figure 2: Bi-directional Signals II
3.1.4
Communication Method via a DB9 Connector
The Master unit usually sends a command to the Slave device via pins 3(+)
and 8(-) and the Slave device responds to the Master via pins 2(-) and 7(+)
Keep the communication path clear between the Master and Slave units in
both directions, as the Slave device must respond to a command transmitted by
the Master
If the Master receives no response from the Slave, the Master will cancel
the communication with the Slave machine and will sometimes flag 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 will disconnect
3.1.5
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 will mean 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
3.1.6
Automatic Configuration
After connecting the DB9 connectors and cables between the controlled
units, the
VS-4216
automatically configures which pins to use in the DB9
connector according to the assignment of each machine
