Sierra 860, 840, 830 instruction manual Input Signal Connections Controllers Only

Input Signal Connections (Controllers Only)

A 0-5 VDC (4-20 mA optional) set point command input signal al- lows you to set the flow to any desired value within the range of the controller. The set point input signal is a direct linear represen- tation of 0 to 100 percent of the controller’s mass flow full scale value.

For 0–5 VDC set point control, connect a manual-adjust potentiome- ter as shown below. Any potentiometer value between 5K and 100K may be used but is limited to a VDC input signal only. For 4-20 mA or 0–5 VDC set point control, use a PLC or other digital device.

If the set point input is not connected to some type of control device, the valve on/off switch must be activated in the off position. If no set point command is present on the controller when powered-up and the valve is not switched off, the valve will drift wide open.

Figure 2-11.

Local Command Set Point Potentiometer (15-Pin D-Connector)

Figure 2-12.

External Command Set Point Source (15-Pin D-Connector)

Note: Use 15 VDC maximum to produce a 4-20 mA setpoint signal.