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Function Description BIS C-810 / PC
Reading / Writing over the serial interface
Explanation of
selected telegram
contents
Start address and
The start address (A3, A2, A1, A0) and the number of bytes to send
no. of bytes
(L3, L2, L1, L0) are transmitted as ASCII characters. For the start address
a range of 0000 to 8191 and for the number of bytes 0001 to 8192 can be
used. A3 ... L0 stand for 1 ASCII character each.
Please note:
Start a number of bytes may not exced the
data carrier capacity.
Block size
For the 'L', 'P', 'Z', and 'C' commands, the block size B ('0', '1') of the
data carrier has to be sent.
B = '0' corresponds to 64 bytes,
B = '1' corresponds to 32 bytes.
Note:
Preceding the block size is a '1' for the fixed-set head number 1.
Acknowledgement The <ACK> '0' is sent by the identification system if the serially
transmitted characters were correctly recognized and a data carrier is
within the active zone of a read/write head.
<NAK> + 'Error No.' is sent as an acknowledgement if an error is detected
or if there is no data carrier within the active zone of a read/write head.
Start
<STX> starts data transmission.
Bytes
The data are transmitted code-transparent (not converted).
sent
C-810-0-003-0_826044_E_0510.p65
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The BCC block check is formed as an EXOR of the serially transmitted binary characters of
the telegram block. Example: Read 128 bytes starting at address 13.
The command line without BCC is: 'L 0013 0128 10'
The BCC is formed:
'L
= 0100 1100
EXOR
0
= 0011 0000
EXOR
0
= 0011 0000
EXOR
1
= 0011 0001
EXOR
3
= 0011 0011
EXOR
0
= 0011 0000
EXOR
1
= 0011 0001
EXOR
2
= 0011 0010
EXOR
8
= 0011 1000
EXOR
1
= 0011 0001
EXOR
0'
= 0011 0000
EXOR
Block check result:
BCC
= 0100 0100
= 'D'
If necessary, termination using block check BCC can be replaced with a special ASCII charac-
ter. This is:
– Carriage Return 'CR'
Example:
Read 128 bytes starting at address 13.
The command line with 'CR" as a terminator is then: 'L 0013 0128 10 CR'
Variant for
terminating with 'CR'
instead of BCC
Function Description BIS C-810 / PC
Reading / Writing over the serial interface
BCC Block Check
