The Allen-Bradley 1771-IG is a high-performance digital input module. It converts TTL signals from your devices into logic levels. This allows your processor to read status bits accurately.
This module uses an 8-input design for space-saving efficiency. You need two power sources for operation. The backplane provides one source, and you supply a 5V DC source.
Product Procurement & Buyer Guide
The 1771-IG solves specific interface challenges in automation. It handles TTL and BCD encoder signals. This makes it perfect for high-speed counting and position sensing.
You must verify your system power supply. The module needs a customer supply of up to 500mA. It draws only 122 mA from the backplane. This keeps your power budget low.
Check your chassis compatibility before purchase. You need a 1771 I/O chassis with a processor. Keying bands on the module prevent wrong slot installation. The bands sit between pins 34 and 36.
The operating voltage range is very tight. You must provide 5.0 to 5.3 Volts DC. Using the wrong voltage will cause operational failure. This module does not work with AC power.
Step-by-Step Installation Guide
First, mount the module into a free slot. Use the correct keying bands to align it. The module supports ½, 1, or 2-slot addressing. Choose the right mode for your system.
Next, connect the wiring arm. Use the 1771-IG with a 1771-WC wiring arm. This lets you replace the module without rewiring. It saves significant maintenance time.
Wire your TTL signals to the correct terminals. The module includes eight status indicators. These lights show active TTL voltages. Use them to verify your field wiring.
Always power the chassis backplane first. Then apply your external 5V DC supply. The signal delay is very fast. Expect an on delay of less than 1 ms.
The off delay is longer for filtering. It measures 20 (+/- 9) ms for DC signals. This built-in filter reduces noise. It protects your processor from false readings.
Logistics & Standard Packaging Details
