![Dycor SmartVue Process Control Monitor Скачать руководство пользователя страница 46](http://html.mh-extra.com/html/dycor/smartvue-process-control-monitor/smartvue-process-control-monitor_operators-manual_2545949046.webp)
SmartVue Operator’s Manual
36
10-0004-R13
7.4
Using the Digital Outputs
One or more digital outputs can be controlled by a Process so that its logical state is
toggled when a specific threshold value is reached. They can thus be used to turn other
connected devices or indicators on or off when a certain measured signal condition is
met. This function can work in one of three modes, depending on the type of source
process that is selected: Threshold, Latching, and Switching. When you want to
manually control a digital output you can also set it to a fixed value: on or off.
A digital output can be enabled or disabled to link or unlink it from a process if need be.
When it is disabled, it will not be controlled by the process it is associated with.
The digital outputs are open collector to ground. When a digital output is turned on, the
open collector circuitry sinks to ground so that whatever device you may have connected
to it will conduct a current and thus be turned on. If needed, internal pull-up resistors can
be enabled to provide a pull-up of +10 to +30 volts through an internal reference diode.
This is accomplished through the
Configure I/O, Multipurpose I/O setup screen.
7.4.1
Threshold Mode
Figure 7-5 shows the configuration screens for a digital output for which the state
depends on an analog input (in this case a current loop input). With the
Mode configured
as
Threshold, when the HiZ threshold is surpassed, the assigned digital output will go
high. Likewise, when the low threshold
Figure 7-5 Digital output configuration screens
In the example figure above, DIO 5 will turn on as the pressure rises above 100 psi and
turn off as the pressure falls below 10 psi.
Hysteresis is possible by specifying both a low and a high threshold value. This is
helpful when the signal that controls the digital output crosses the threshold frequently
within a short period of time producing a chattering effect. An inverted polarity
characteristic is possible by setting the
Low Threshold value larger than the HiZ
Threshold value.