Able Planet 620DuN 23.2 Scaling: analogue input 2

Watson-Marlow 620DuN and 620Du User Manual 69

4-20mA circuit impedance: 250Ω.

For voltage modes, a stable, reliable voltage source can be used with a DC voltmeter.

Circuit impedance: 22kΩ.

Inverting the response is set up in software. Do not invert the polarity of the pins.

A remote potentiometer with a nominal value of between 1k and 2k with a minimum

of 0.25W should be wired as shown. When using a remote potentiometer, do not

apply a voltage or current control input signal at the same time. The speed control

signal will require calibration relative to the minimum and maximum settings of the

potentiometer. This is done in software - see 18.1 Trim in the Setup section.

When using a remote potentiometer, it is important to set the analogue input to volt-

age in the Setup menu. Otherwise the reference voltage supply from pin 21 will be

overloaded and will not provide a full 5V or 10V.

23.2 Scaling: analogue input 2

It is possible to scale the speed of the pump remotely by one of these methods: a

voltage analogue signal within the ranges 0-10V or 1-5V; or a current analogue sig-

nal within the range 4-20mA; or a remote potentiometer.

The analogue scaling signal must be applied to pin 22 of the lower D-connector. 0V

to pin 20. The speed of the pump as set by Analogue 1 is scaled in proportion to the

signal from Analogue 2 according to the formula y=as, where a is the speed set by

Analogue 1, s is the scaling set by Analogue 2 (0V or 4mA = 0, increasing linearly

to 10V or 20mA = 1), and y is the scaled rotation speed. If Analogue 2 has been set

for an inverted response, the reverse is true. See 18.2 Analogue in the Setup menu.