External Control - Analog Input - White Knight PPMC300 Owner's Manual

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Table of Contents

cycle rate (which needs to be specified at the time of purchase), or from the internal potentiometer that can be

accessed from inside the electrical enclosure (see below in section 5.2.1.1.). A device that was not previously set

in Plug-n-Play operation can be modified to operate to perform in this manner, and if a pump was set in plug-n-

play, and was not hard coded, can be modified to accept external controls.

5.2.1.1

Switching Between Plug-n-Play and External Control:

a small flathead screwdriver and rotate the potentiometer to the desired position. Rotating clockwise will decrease

the cycle rate, and rotating counter-clockwise will increase the cycle rate.

Note: there are no hard limits. After reaching minimum and maximum cycle rates the potentiometer will continue

to rotate without changing value. Full range of the cycle rate requires multiple turns to achieve.

Note: the potentiometer can be adjusted while the power is on, to assist in properly tuning the cycle rate.

However, care should be taken to not short circuit the circuitry.

Note: A revision change in 2022 inverted the rotation direction of the potentiometer to increase and decrease

cycle rate. If the desired effect is not achieved, attempt to rotate in the opposite direction.

After the potentiometer is set in either the Plug-n-Play operation, or in External Control operation the electrical

cover should be replaced being careful to not pinch any wires. Tighten the socket head screw caps until they are

snug; do not over tighten, as this could strip out the plastic housing. Replace the screw cap covers.

5.2.2 External Control - Analog Input

With the Plug-n-Play control disabled, then the pump is in external control. At this point the imbedded controller

watches its analog input and will vary its cycle rate depending on the signal received. Analog input signal is 0-5

VDC with the common ground from the power input is the reference voltage for the analog input signal. The

analog input is interpreted as follows:

•

0-1 VDC: Pump will not operate.

•

1 VDC: is the transition from on to off, and should be avoided as a signal input, as the pump may toggle

between the on and off position and will not flow.

•

1-5 VDC: Pump will operate based upon the voltage to cycle rate conversion equation below.

�� = 100 ∗ �� − 100

This equation outputs a linear cycle rate output below are some example voltage to cycle rates:

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To switch the operation mode of

the PPMC300, the electrical cover

will need to be removed. To

remove the cover, remove the

cap screw covers and the two cap

screws that hold the electrical

cover in place (shown in image to

the left). Once the cover has been

removed find the surface mount

potentiometer on the circuit board

(Shown in image to the right). Use

1.1 VDC = 10 CPM