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Below is an illustration of digital input and keypad use. The example is for the Control Enable function. Other func-
tions behave in a similar way.
Unit
Start-Up
Control Function
Control Enabled
Control Disabled
Digital Input
Signal High
Signal Low
HMI
Menu – “ON”
Menu – “OFF”
1. On start-up, the unit uses the Power-Up Action for
its initial control state. In this example, it starts in the
disabled condition.
2. Digital input signal changes from Low to High;
therefore, control becomes enabled. The Control
Enable parameter will say ON, when viewed from
the HMI (front panel).
3. The keypad on the HMI (front panel) menu is used
to change the control back to disabled, Control En-
able parameter = OFF.
4. The digital input changes state, going from High
to Low, but as the control is already disabled no
change is made.
5. Then the digital input goes from Low to High again,
re-enabling the control. The Control Enable param-
eter in the HMI also shows control is ON again.
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