Sierra Not available instruction manual

Series 900 Single & Dual Instruction Manual

The VALVE PURGE function is activated by the VALVE TP (test point) pin. When this pin is connected to common, the valve is fully open regardless of setpoint. This pin must source 150 mA of current when driven to common. If a voltmeter is connected between this pin and –15 VDC, the voltage across the valve coil may be read. Refer to Appendix C for pin assignment.

The 26-pin connector has two optional alarm outputs per channel. One is active when the flow drops below a preset value (low alarm). The other is active when the flow increases above a preset value (high alarm). All alarm outputs are open collector. Maximum current is 100 mA per alarm. Maximum “standoff” voltage is 30 VDC.

CAUTION! If a relay is being driven by an alarm, A protection diode must be connected across the relay coil with reversed polarity.

A high and low alarm may be connected in parallel to make a window alarm. Whenever the flow is inside of the window defined by the two alarms, the alarm is inactive (OFF). If the flow is outside of the window, the alarm is active (ON). See Appendix D for suggested alarm configurations.

There are two plastic programming jumpers plugged into a header on the back panel. For each channel they determine whether the 0-5 VDC setpoint input comes from the front panel pots (MANUAL) or from the 26-pin I/O connector (AUTOMATIC). These jumpers are easily changed in the field simply by unpluging them and moving them to the other position. The system will not function as a control box for mass flow controllers without these jumpers.

4.3.3 High/Low Flow Alarm Outputs

4.4

Automatic/Manual Setpoint Selection (Controllers)

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