Response Electronics CL6011B Spécifications télécharger pdf (Page 79)

3Ć59 Theory of Operation: Self Test

Original Ć June 1990

CE4.2:CL6211

3.7 Controller Self Test

The controllers perform checks on internal operation of various

subsystems, as outlined below. All of the self test checks are performed

periodically in a background state, at a priority lower than any other

function that the controller is required to complete.

3.7.1 Ram/Rom Check

Periodically the Random Access Memory (RAM) and Read Only Memory

(ROM) are checked for normal function. The RAM check is a read/write

check, performed when no other operations are going on. The ROM

check performs a cyclic redundancy checksum across various segments

of the ROM to insure that no detectable data alteration has occurred.

3.7.2 Non-Volatile Memory Check

The controllers retain their application configuration in a non-volatile

memory (NVM) storage device, which requires no power supply to retain

the data. Data retention of these un-powered devices can degrade over

time, and the controllers are designed to retain the configuration data for

a minimum of 24 hours in a non-powered state. Actual data retention

can far exceed this minimum requirement.

The NVM check performs a periodic checksum validation of the

configuration information, and operating parameter restart values.

3.7.3 Analog Output Self Test

Periodic checks are performed on the analog output subsystem to

assure that the intended analog signals are actually being transferred to

the terminations. There is special circuitry incorporated on the controller

units to allow a detection of the current signal being sent out of the

current driver subsystem. This allows an actual current output self test to

measure the current value being issued from the controller, and then

compare this value to the intended signal. Any sustained deviation

greater than 4 percent will cause an analog calibration error to be

signalled.

Also, there is an on-board voltage reference source, that allows the

controller to determine if the calibration of the input/output subsystem

has exceeded 4 percent. If this voltage reference error is detected, an

analog calibration error is signalled.

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Response Electronics CL6011B Spécifications Page 79