Rockwell Automation 1771-IGD TTL Input Module Installation Instructions - Manual (Page 5)

TTL Input Module 5
Publication 1771ĆIN022B-EN-P - September 2002
Your module is preset to the positive-logic level. Use the following
table to choose between the two logic levels:
If youchoose: Then: Jumper Position
HIGH = TRUE logic (positive) 2.0 to 5.25V dc corresponds to logic ``1" (on) Toward rear of module
LOW = TRUE logic (negative) -0.2 to 0.8V dc corresponds to logic ``1" (on) Toward front of module
Note: Selecting positive logic automatically enables the HIGH (positive logic) indicator.
You select high-true or low-true using the jumper accessible through
a slot at the top of the module.
1. Locate the jumper in the slot at the top edge of the module.
2. Use tweezers to position the jumper as required for your
application.
When on front 2 pins, negative logic
selected (low = true).
TTL Input Module
When on rear 2 pins, positive logic
selected (high = true).
1044
TTL Logic Level Selection Jumper Assembly
Setting the Logic Level