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Checking the Data Carrier Life
5-4
Checking the Data Carrier Life
5-4-1 SRAM-type Data Carrier
Checking Battery Voltage Drop
1, 2, 3...
Battery Life of Data Carrier
5-4-2 EEPROM-type Data Carrier
54
1. A voltage drop of the battery cannot always checked but can be checked
only when specific access is made.This is because, to check the battery
voltage, a certain amount of current is temporarily allowed to flow through
the internal circuit of the data carrier. If the battery voltage is checked each
time the data carrier is accessed, the battery life is shortened. It is recom-
mended that a routine that checks the battery once a day be incorporated in
the system program.
2. Access to check battery voltage:
The battery is checked only when the 2-byte data of addresses 0000 and
0001 are is read.
<Battery voltage check command>
a) Read command ...
b) Auto read command ...
c) Polling auto read ...
d) Expansion read command ...
3. Response when battery voltage drops:
If the battery voltage has dropped, "7B" is returned as the end code of a re-
sponse.
Example:
Normal state
RD 0 0
0 9 9 0 *
AR 0 0
0 9 9 0 *
Normal completion code
When battery voltage drops
RD 7 B
0 9 9 0 *
AR 7 B
0 9 9 0 *
Battery error code
The Data Carrier can still be used for about 1 month under ordinary operating
conditions, even if the voltage of the battery has dropped below the rated level.
However, it is recommended that the data carrier battery be replaced with a new
one as soon as possible.
The MDL command checks whether or not the EEPROM of the Data Carrier has
been overwritten 100,000 times. By adding an appropriate number of overwrit-
ing operations with this command to the management area specified by the user,
whether or not the EEPROM has been overwritten 100,000 times will be known.
RD H 1 0000 02
AR H 1 0000 02
PR H 1 0000 02
XR H 1000 02
Read data
Produced in Sept., 1990
Read data
Produced in Sept., 1990
Section
5-4
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