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19
Diagnostic Self-Test (Check Sum)
With this procedure it is possible to:
calculate the tariffs check sum
print out the tariff program.
verify segment display correct functionality
How to enter the Self- Test function
The Check Sum
To test Data Integrity, the Tariff Data is signed with a CRC16 function.
A 16 bit CRC Check Sum is therefore calculated from the Tariff Data, and saved for a future reference. The only two sections
that are out from the check sum are the unique vehicle and owner parameters, like: "k" constant and ticket heading.
a)
Tariff Programming through PC or Smart key: if the data buffer is corrupted, due to errors in data transmission,
system errors or tampering, the CRC16 Check Sum will be different from that stored for comparison.
b)
At each Trip the Taximeter recalculate the Checksum of the Tariff and compares with the stored CS. reference;
and in case of data corruption it auto locks the meter showing at any tentative of start a trip the message "Error
Csum" so it can' t work with a wrong tariff until reprogrammed.
c)
It is possible to recalculate the check sum manually, IE, by Inspectors in every moment but only when the meter
is in FOR HIRE mode, by pressing together K1 + K4, to verify that the meter is programmed with the right tariff.
The CRC16 Check Sum is a number between 0 and 65535, and can be displayed on the Taximeter when wished.
ALGORITHM SHORT DESCRIPTION:
The CRC 16 Check Sum calculation in the Taximeter is the (CCITT CRC16).
The polynomial used is:
Hex : 0x1021
Bin : 1000000100001
Dec : 4129
Register Init is Hex : 0000
CHECK = Hex : 31C3
Select For Hire position.
Press K1 and strike K4.
Both displays will show in sequence the numbers from 0 to 9 in
all display digits. Check if all numbers are correct.
After that, an 8 digit will be shown moving from right to left,
verify that only one digit at a time is on, otherwise there might
be some short circuit between LEDs.
The printer, if connected to the taximeter and powered on, will
print out all the taximeter setup.
To increase the start block number press K2 button before print
start, in this way tariff block 0 will not be printed (to reduce
report length).
To print also ProgDates records, press K1 button before print
start. ProgDates report will be printed after tariff one.
After a few seconds the main display will show the tariff
checksum (CRC16 of all tariff parameters) so that each tariff will
have its own resulting checksum value. The secondary display
will show the firmware country version.
At the end of procedure the taximeter will go back in For Hire
