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Operation
Configuration
3
3-4
3.3 Operation
Operation of the 943-227-15 Digital Preamplifier is automatic and is controlled by the Model 942A-200C
Digital Ratemeter or Model 960 Digital Process Radiation monitoring system. Once the power to the
controlling device is turned on, the preamplifier begins operation. No operator interaction is required.
Refer to the instruction manual for the applicable controller, detector and the Model 942-200-80
Communications Option Board for further information.
Normal Operation
If the measured radiation field is within the range of the detector during power-up, the uCi/cc value will be
displayed on the controller. The digital display will update once per second.
Alarms
The radiation alarms are initiated by the applicable controller. Refer to the applicable controller manual.
Fail Alarm
There are two equipment failure conditions that can produce a FAIL output or an error display on the
associated controller. The fail condition is true whenever any equipment failure is detected and false
when no equipment failures are detected.
The following are the fail alarms provided by the 943-227-15 Preamplifier:
1. POWER Failure
2. Loop Test Failure
To return the channel to normal operation after a FAIL alarm, the condition, which caused the alarm, must
be located and corrected.
Power Failure
If the power to the controller is lost, the bar graph, alarm indicators, and the display are blanked (turned
off). The HIGH, WARN, and FAIL relay coils will de-energize. If power to the preamplifier only is lost, or if
there is a break in the power cable, operation of the microprocessor will stop. The display on the
controller will then cease to update. If power to the controller is not lost, a break in the interconnecting
wiring or the internal communication power fuses on the 977-210-10M Interface board should be
checked. Loss of power to the preamplifier will also result in a loop communication failure.
Loop Failure
If the UDR or 960 controller does not receive a valid message from the preamplifier in ten seconds, a loop
failure is detected and an E0009 code will normally be displayed. Note the error code displayed is
defined by the controlling device, and not by the preamplifier.
The loop failure can originate from bad seating of the serial communications board in the UDR or 960CD,
bad connections in the preamplifier, bad connections at the P2 connector of the UDR, a baud rate
mismatch between the setting on the serial board and that in the preamplifier, an invalid address setting
on the serial board, or blown communication loop fuses.
The baud rate of the preamplifier may be set to either 300 or 4800 baud. SW3-1 on the 977-interface
board must be in the ON position to select a baud rate of 4800 baud, the normal setting.