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Installation Instructions
This document provides information on:
important pre-installation considerations
power supply requirements
initial handling procedures
installing the module
using the indicators for troubleshooting
module specifications
You can use any TTL device that meets the input logic level specification
of -0.2V dc to +0.8V dc (low), and 2.0V dc to 5.25V dc (high).
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.
Backplane
The TTL module receives its power through the 1771 I/O chassis
backplane from the chassis power supply. The module requires 168mA
from the output of this supply. Add this to the requirements of all other
modules in the I/O chassis to prevent overloading the chassis backplane
and/or backplane power supply.
Customer Supply
You must provide a separate +5(+0.25)V dc power supply for TTL outputs
from the module and for your TTL input devices. Your module requires
250mA from the output of your supply. Ripple should not exceed 50mV
peak to peak.
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Summary of Contents for Allen-Bradley 1771-OG
- Page 1 Installation Instructions This document provides information on: important pre-installation considerations power supply requirements initial handling procedures installing the module using the indicators for troubleshooting module specifications You can use any TTL device that meets the input logic level specification of -0.2V dc to +0.8V dc (low), and 2.0V dc to 5.25V dc (high). 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.
- Page 2 The TTL output module is shipped in a static-shielded bag to guard against electrostatic discharge damage. Observe the following precautions when handling the module: ATTENTION: Under some conditions, electrostatic discharge can degrade performance or damage the module. Observe the following precautions to guard against electrostatic damage. Wear an approved wrist strap grounding device, or touch a grounded object to discharge yourself before handling the module.
- Page 3 Remove the side cover from the module by removing the screw at each of the four corners. Set the switches as needed for your application. Reinstall the cover and secure with the four screws. Use the plastic keying bands, shipped with each I/O chassis, to key the I/O slots to accept only this type of module.
- Page 4 To install the TTL output module in your 1771 I/O chassis, follow the steps listed below: ATTENTION: You must first turn off power to the 1771 I/O chassis backplane and field wiring arm before removing or installing an I/O module. Failure to turn off power to the backplane or field wiring arm could cause personal injury, module damage, or degradation of performance.
- Page 5 Separate the shielded cables from wiring that radiates electrical noise. Refer to category 2, low power dc I/O lines, in publication 1770-4.1, ‘‘Programmable Controller Wiring and Grounding Guidelines”. Prepare the cable for grounding by doing the following: Ground the single strand (at the ground lug end) to the grounding stud on the I/O chassis or by using single-point grounding.
- Page 6 Connect the insulated wires to their respective terminals on the field wiring arm. Output terminals of the TTL output module (cat. no. 1771-OG) may directly drive inputs of a TTL input module (cat. no. 1771-IG). Connect the cable shield between modules at one end only.
- Page 7 The front panel of your module contains nine status indicators (Figure 1). The red top indicator is labeled ‘‘HIGH = TRUE.” When on, it indicates you selected high-true logic (SW1 on and SW2 on). When off, it indicates you selected low-true logic (SW1 off and SW2 on). Each of the lower eight red indicators light when their corresponding output terminal delivers TTL voltages in the true state.