Flowserve Logix 1200e LGAIM0044 - Manual (Page 37)

Flowserve Corporation, Valtek Control Products, Tel. USA 801 489 8611 44-37
Alarms
Introduction
The Logix 1200 positioner has several internal alarms
that monitor electronics operation. An internal alarm
causes the red LED to blink. Alarms can be viewed in
the Alarm screen of ValTalk software, View Alert dis-
play (by right-clicking on the alarm LED in the lower
right-hand corner of any screen), Alert Details button
with SoftTools TechCheck, or by using the Hot Key
with the HART 275 handheld communicator. ‘Alarms’
differ from ‘alerts’ in that the action of the positioner
may be erratic during the alarm conditions, while
alerts warn a predefined, user-configured condition
has occurred that may require service in the near
future. Alarms cause the red LED to blink, while alerts
cause the yellow LED to blink.
12-bit A/D Reference Alarm
The Logix 1200 positioner utilizes a 12-bit analog-to-
digital (A/D) converter to acquire command and stem
position readings. If the precision reference used by
the A/D drifts outside rated tolerances, the 12-bit A/D
Reference Alarm will become active. A reference error
will cause change in calibration and control readings.
If a continuous 12-bit A/D Reference Alarm exists, the
main PCB assembly must be replaced. Refer to spare
parts kit numbers section.
1.23 V Reference Alarm
The 1.23 V Reference is used by the inner loop spool
position control. If it drifts outside normal tolerances,
the 1.23 V Reference Alarm will become active. If a
continuous 1.23 V Reference Alarm exists, the main
PCB assembly must be replaced. Refer to spare parts
kit numbers section.
12 bit D/A Alarm
The Logix 1200 positioner utilizes a 12-bit digital-to-
analog (D/A) converter to send a control signal from
the micro-controller to the inner loop spool positioning
circuit. The output of the D/A converter is indepen-
dently measured to verify correct operation. A 12-bit
D/A Alarm indicates the D/A may be malfunctioning. If
a continuous 12-bit D/A Alarm exists, the main PCB
assembly must be replaced.
Temperature Alarm
The main PCB assembly contains an ambient
temperature sensor. If the ambient temperature
reading moves outside the operating range (-40° F to
185° F/-40° C to 85° C), the Temperature alarm
becomes active and the red LED blinks. If this alarm is
present and the ambient temperature reading is
incorrect, the main PCB assembly must be replaced.
Refer to spare parts kit numbers section.
Hall Sensor Alarm
As described in the Theory of Operation, the Logix
1200 positioner incorporates an inner loop, spool-posi-
tioning stage. A hall sensor is used for spool control. If
the electronics sense a problem with the sensor, the
Hall Sensor Alarm becomes active. Two common rea-
sons for a Hall Sensor Alarm are a loose or missing
cable connection to the Collector Board Assembly or a
broken wire. In the rare event that the actual hall sen-
sor is defective, the driver module assembly must be
replaced. Refer to spare parts kit numbers section.
Modulator Current Alarm
The pressure modulator is an electro-pneumatic
device that takes a current signal from the electronics
control and generates a pressure that moves the
spool. The Logix 1200 positioner is a loop-powered
device that must run on very low power. During opera-
tion, the pressure modulator current is monitored. If
the current draw is not within acceptable parameters
for the given control mode, the Modulator Current
Alarm becomes active and the red LED blinks. The
magnitude of Modulator Coil Current can be viewed as
Variable No. 97 in the Instrument Status screen (Val-
Talk software), the Condition screen under View Vari-
ables (SoftTools TechCheck software) or in the
Status/Technician screen (HART 275 handheld com-
municator). Listed below are some reasons for a Mod-
ulator Current Alarm:
• Pressure modulator minimum pressure too low
• Clogged or restricted orifice
• Malfunctioning or missing cable connection to col-
lector board assembly
• Stuck or sticky spool
• Internal air leaks from tubing, orifice gasket or pres-
sure modulator