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ROC800-Series Instruction Manual
4-12
Input/Output Modules
Revised Jul-14
4.6 Pulse Input (PI) Modules
The Pulse Input (PI) module provides two channels for measuring either
a low speed or high speed pulse signal. The PI module processes
signals from pulse-generating devices and provides a calculated rate or
an accumulated total over a configured period. Supported functions are
slow-counter input, slow rate input, fast counter input, and fast rate
input.
The PI is most commonly used to interface to relays or open
collector/open drain type solid-state devices. The Pulse Input can be
used to interface to either self-powered or ROC800-powered devices.
The high speed input supports signals up to 12 kHz while the low speed
input is used on signals less than 125 Hz.
You can configure the PI module as either 12 or 24 Volts dc using
jumper J4 on the I/O module (see
Figure 4-10
). The PI modules can
provide isolated +12 Volt dc or +24 Volt dc field transmitter power on a
per-module basis. For example, one module can provide +12 Volt dc
power, while another module in the same ROC800 can provide +24
Volt dc power. Refer to
Figures 4-11
and
4-12
.
The PI module provides LEDs that light when each input is active.
Caution
The Pulse Input module is designed for use with “dry” relay contacts or
solid-state switches. Applied voltage in excess of 24 Vdc may damage
the module.
The PI modules draw power for the active circuitry from the backplane.
Input signals are optically isolated.
Note
:
Do not connect wiring to
both
the Low and High speed
selections for a given channel. This results in unpredictable
operation of the PI module.
A
+T 12 / 24 V dc Jumper
Figure 4-10. Pulse Input J4 Jumper (Set to +12 V)
A