3-2SectionData Carrier Memory Map
22
3-2-2 Production Date Format
The
production date format is valid for a DC with a memory capacity
of more than
256 bytes.
For
checking the life of the DC battery
,
the manufacturer registers the production
date
in
the first two bytes of the memory area immediately prior to shipping the
DC
from the factory
. Data can be read from this area, but cannot be written to it. If
a
write operation
to this area is attempted by mistake, an error message, “7D,”
will be issued.
Production Date Control Area
Address Bit
7 6 5 4 3 2 1 0
0000 Month, first digit Month, second digit
0001 Year, first digit Year, second digit
Note 1. The last two digits of the year is used. For example, 92 for 1992.
2. The
month is represented by two digits. For example, 03 for March and 10
for October.
Example
In the case of September 1992, the bits are as follows:
Address Bit
7 6 5 4 3 2 1 0
0000
0 0 0 0 1 0 0 1
0 9
0001
1 0 0 0 1 0 0 1
9 2
Note A
DC with a memory capacity of 256 bytes or less does not have a production
date (month and year) area. The first address of such a DC is a write protect
area.
3-2-3 Write Protect Function
The write protect function protects important data stored in the memory of the
Data
Carrier
, such
as product number and model, from inadvertent write access.
With
this function, the data up to a specified memory address can be protected. It
is recommended that important data be write-protected as follows:
Memory of 256 Bytes or Less
Setting Write Protect FunctionThe
write protect
function is set in address 0000 of the Data Carrier
’
s memory
.
The
most
significant bit (MSB) of address 0000 determines whether or not the
write protect function is in effect.
Address Bit
7 6 5 4 3 2 1 0
0000 YES/
NO
Last 2 digits of end address
Write protect execution bit (most significant bit of address 0000)
1: Write-protected
0: Not write-protected
The
end address can be set between 00 and 7F
. Setting the address
to 00 pro
-
tects
all bytes from 0001 through 00FF
. Setting the address to a value from 01 to
7F
protects all bytes from 0001 through the specified address. It
is not possible
to specify an end address between 0080 and 00FF.
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