User's Manual

Communication
and Control
This section describes communication with the IPL T CR48 as well as A/V device control.
Topics that are covered include:
 Ports Overview
 Communication with the Interface
 Programmer’s Guide for the Telnet and Web Browser
 Device Control
 Troubleshooting
Ports Overview
Contact Closure Input Ports
The contact closure inputs on the IPL T CR48 are able to detect a closed circuit between any
of the inputs and ground. The contact closure input ports use a 1k ohm pull-up resistor in a
TTL (5 VDC) circuit to sense external switch or contact closure.
By connecting one side of an external switch or relay to the contact closure ground port
and the other side to one of the four contact closure input ports, logic 1 (closed) can be
produced. Logic 0 (open) can be produced by disconnecting either side of the external
switch or relay from the IPL T CR48.
+5V
1K
Figure 12. Equivalent Circuit for Contact Closure Input
IPL T CR48 • Communication and Control 15