Dwyer DPM - Manual (Page 33)

Particulate Monitoring Systems
Installation & Operating Manual
Document No. 210-1003-M Page 26 ©2007
8. Automatic Self Checks
An optional self check subsystem is available to automatically verify calibration and proper operation
of the electronics, sensor and cable. Self checks can be performed while the system is online and
monitoring particulate. No external test equipment or operator intervention is required to activate or
complete the self check routines. Any errors detected by the self checks are reported through the
display, 4-20mA, relay and Modbus® outputs. The following automatic self checks are performed:
• Control Unit Hardware Check
• Control Unit Calibration (Zero and Span)
• Sensor Cable Check
• Particulate Sensor/Probe Check
The control unit zero and span self checks that are performed meet all requirements of the EPA
MACT Quality Assurance specifications. Self checks are automatically run every hour. A manual Self
Check may be activated anytime through the control unit keypad.
8.1 Control Unit Hardware Check
The Control Unit Hardware Check is an automatic check of all major electrical components in the
control unit. This check is automatically performed each time power is applied to the control unit.
Check Description
Watchdog Timer
Monitors all program tasks running in the microprocessor and
automatically resets the processor in the event of lock-up.
SRAM Checks the integrity of the SRAM memory.
Non-Volatile
Memory
Checks the integrity of the Non-Volatile memory. The results of this
check produce a checksum value which is analyzed each time a non-
volatile memory write occurs.
Option Board
Checks for proper installation of Power Supply, RS-485 and Self
Check option boards.
Analog Converter
Calibration
Checks calibration of the 22 bit high resolution analog converter.