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Programming the Outputs
10.8 Interlocks
Interlocks are digital inputs that temporarily pause
an output from operating (Relays 1 to 9 and 4-20mA
outputs). Typically, a cooling tower control program
will include a digital input signal from a flow switch.
When the flow switch indicates that no sample water
is flowing, any relay that has this digital input listed
as an interlock will stop operating until the flow is
restored.
Boilers can use 'online' relay dry contact signals to
enable which boilers can be bled or have chemicals
fed to them.
10.8.1 Setting/Removing Interlocks
1- From the MENU page, scroll down to I/O
Setup and press OK
2- Scroll down to the relay you wish to edit and
press OK
3- Scroll down to 'Interlock' and press OK
4- Scroll up and down to see all available
interlocks (digital inputs configured as
Contact Set) Press F1 to select.
5- The block █ symbol indicates that this input
is currently selected.
From this screen, you can choose multiple interlocks
or remove them. Once an interlock is chosen, the F1
key will remove it.
Notice the F2 key says 'OR'. This means if any one
of the interlocks are 'ON', (shorted) the relay will be
paused. If you press F2, the 'OR' will change to
'AND'. AND means all interlocks chosen must be ON
to produce the pause. Multiple Interlocks are not
typical.
Any one interlock can be used on multiple relays
and 4-20mA outputs. Typically, all outputs on a
cooling tower are paused by the flow switch input.
Page 74 of 102
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