TTL Input Module
Cat. No. 1771IGD
Installation Instructions
7
The front panel of your module contains 18 status indicators (Figure 1).
The green top indicator is labeled ‘‘ACTIVE.” This indicator is on when
the fuse is good. The green bottom indicator, when on, indicates you
selected high-true logic. When off, it indicates you selected low-true logic.
Each of the 16 red status indicators light when their corresponding input
terminal senses TTL voltages in the true state.
Figure 1
Status Indicators
ACTIVE
00
01
02
03
04
05
06
07
10
11
12
13
14
15
16
17
Module Active Indicator (green)
00 to 17 Status Indicators (red)
HIGH
Positive Logic Indicator (green)
10451I
To replace a blown fuse, proceed as follows:
ATTENTION: Remove power from the 1771 I/O chassis
backplane and field wiring arm before removing or installing an
I/O module.
Failure to remove power from the backplane or field wiring
arm could cause module damage, degradation of
performance, or injury.
Failure to remove power from the backplane could cause
injury or equipment damage due to possible unexpected
operation.
1.
Turn off power to the chassis.
2.
Remove the module from the I/O chassis.
3.
Remove the blown fuse from the fuse holder (accessible through the
slot in the side cover), and replace with a 0.5A, 250V normal
blow fuse.
4.
Reinsert module into the I/O chassis.
5.
Turn on power to the chassis.
Interpreting the Status
Indicators
Replacing the Fuse
