Active LED

The Active LED will be illuminated when the module is functioning normally. If the Active

LED is not lit, or if it is blinking, refer to Chapter 3 for troubleshooting.

Asynchronous Operation

The module operates asynchronously with respect to the PLC.   The controller is

programmed to monitor and control the operation of the High Speed Counter module using

the words and bits provided in the module interface.  The module provides reset, inhibit,

output, and counter status in three WX input words.  The controller uses 5 WY output words

to control counting, control outputs, and set counter presets.

Inputs

The 2502 Two-Channel High Speed Counter Module has two independent counting

channels.  Each channel has four inputs. Each input may be used as either sinking or

sourcing (with external 5–24 VDC power supply). The input signals are connected to the

field wiring terminal block.

Reset – Current flow through the reset input sets the channel’s counter to

zero. The counter will be held at zero until the reset input becomes

inactive.

Inhibit – Current flow through the inhibit input inhibits the channel from

counting. The counter holds at the last value and does not change until the

inhibit input becomes inactive.

Counter Input A, Counter Input B – The relationship of the states of these two inputs,

combined with the counter mode setting, determines the direction of the count. Typical

devices for counting are high-speed static switches or incremental encoders.