MKS UniMag 971, Operation And Installation Manual, Page: 18 / 44

971 UniMag ™ Operation manual 15
The cold cathode sensor must be turned on before the transducer can provide pressure measurement
values. The 971 can be controlled via digital interface, external analog control or manually.
P/N: 971-x1090-0001, will always enable the high voltage when power is turned on. Power supply
must be external controlled by switching power (pin 4) on and off to avoid continuously operation
at high pressure.
Digital Control of Cold cathode
Turn on Cold Cathode high voltage:
Command: @253FP!ON;FF
Command values: ON, OFF, ALWAYSON
Command reply: @253ACKON;FF
Query: @253FP?;FF
Query reply: @253ACKOFF;FF
Factory default: OFF
If FP is set to “ALWAYSON” the Cold Cathode high voltage will be turned on immediately when the
transducer is powered on. Use power supply to control the transducer and prevent operation at higher
pressure.
Analog Control of Cold cathode
The cold cathode can be controlled by external equipment by shorting pin 13 to power supply ground pin 4.
The analog controller can either be momentarily pulse trigged or low level trigged.
Analog Level trig (factory default)
When enabling level trig the cold cathode sensor will be on when
pin 13 is shorten to ground pin 4 and turned off when pin 13 is
floating.
Enabling level trig:
Command: @253SW!OFF;FF
Command reply: @253ACKOFF;FF
Analog Pulse trig
When enabling pulse trig the cold cathode sensor will be turn on when cold cathode enable (pin 13) is
shorten momentarily to ground (pin 4) and turned off when cold cathode enable (pin 13) is shorten
momentarily to ground (pin 4) again.
Enabling pulse trig:
Command: @253SW!ON;FF
Command reply: @253ACKON;FF
Query: @253SW?;FF
Query reply: @253ACKON;FF
Factory default: OFF
Cold cathode external control pin 13 must be floating or shorten to power supply
ground pin 4. Do not connect to a voltage source.
Connection to voltage source can cause permanent damage to the transducer.
Manual Control of Cold cathode
The cold cathode can also be controller by pressing the user switch. The Cold Cathode
can either be activated or deactivated by pressing the switch momentarily (SW!ON) or
activated while pressing down the switch (SW!OFF). The 971 is per factory default
delivered with SW turned off.