ID
Installation Data
TTL Input Module
Cat. No. 1771IGD
Installation Instructions
This document provides information on:
important pre-installation considerations
power supply requirements
initial handling
installing the module
using the indicators for troubleshooting
replacing the fuse
module specifications
You can use this module in a Series A or B 1771-A1B, -A2B, -A3B,
-A3B1, and -A4B chassis. The module is also compatible in a 1771-AM1
or -AM2 I/O chassis.
You can use any TTL device that meets the output logic level specification
of -0.2V dc to +0.8V dc (low), and 2.0V dc to 5.25V dc (high).
This module contains input filtering to limit the effects of voltage
transients caused by contact bounce and/or radiated electrical noise.
The delay due to filtering is less than 1ms.
For maximum noise immunity, the output of the TTL device should have a
pull-up resistor of 1k ohm (typical). Add an external pull-up resistor to the
output terminals of the device, if necessary. If you add a pull-up resistor, be
sure the TTL device maintains the low state requirement of -0.2V dc to
+0.8V dc with the increased load.
The TTL module requires power from two sources: the I/O chassis
backplane, and a +5V dc power supply that you provide for transmission of
TTL signals.
To The Installer
Preinstallation
Considerations
Power Requirements
