External Boolean Module

The External Boolean module provides a single Boolean register that you can define as either on or off.

Module icon


If you want to disable a module under certain circumstances, you can link its Enable input to an External Boolean module that you can switch to off.

NOTE: The registers and settings available in this module depend on the device or node you are configuring, as well as its firmware and template versions. Not all registers or settings are available on all devices or the Virtual Processor, and labels may vary.


External Boolean modules have no inputs; they are controlled via communications.

Setup registers

EvPriority (event priority)

This register allows you to assign a priority level to the events produced when the output register is written. When EvPriority is zero, no event is written.

Output registers


All External Boolean modules have a single switch register which can be manually switched on or off via communications.


All events produced by an External Boolean module are written into this register. Possible events and their associated priority numbers are shown in the table below.

Event priority group Priority Description
Setup Change 10 Setup register or labels have changed.
Output Value Written * The Switch output is written.
* The priority of this event is determined by the value in the EvPriority setup register.

The Event output register stores the following information for each ION event: time stamp, priority, cause, effect, and any values or conditions associated with the cause and effect.

Responses to special conditions

The following table summarizes how the External Boolean module behaves under certain conditions.

Condition Response of output registers
When the device is started or powered-up (either the first time, or after a shut-down). The Switch output register retains the value it held at shutdown.

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