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english
Reading and writing
To carry out a read or write job, the Data carrier must be located in the active zone of the read/
write head.
A read/write job has the following sequence (see examples on
38ff):
1. The host sends to the output buffer:
– the command designator to subaddress 01
Hex
,
– the start address for reading or writing to subaddress 02
H
EX
/03
H
EX
,
– the number of bytes for reading or writing to subaddress 04
H
EX
/05
H
EX
,
– the CT bit in the bit header according to the Data carrier type (block size),
– and sets the AV bit in the bit header to high.
2. The processor:
–
takes the request (AA bit in the bit header of the input buffer to high),
–
begins to transport the data;
read = from data carrier to input buffer,
write = from output buffer to data carrier.
Larger data quantities are sent in blocks
(block size with 2nd bit header = buffer size – 2),
block size without 2nd bit header = buffer size – 1).
The toggle bits in the two bit headers are used as a kind of handshaking between the
host and the BIS C-60_2 processor.
3. The processor has processed the command correctly (AE bit in the bit header of the input
buffer). If an error occurred during execution of the command, an error number will be
written to subaddress 01
Hex
of the input buffer and the AF bit in the bit header of the input
buffer will be set.
Function Description
Processing data carriers
C60_2-019_818217_0806-e.p65
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english
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Special
characteristics
Auto-Read
Function Description
Processing data carriers
Codetag Present
As soon as the data carrier enters the active one of the read/write head, the processor indi-
cates this by setting the CP bit (Codetag Present).
To accelerate the reading of small amounts of data, the ID system makes the first bytes of the
data carrier available in the input buffer of the respective read/write head as soon as the tag is
detected (30 bytes with 2nd bit header, 31 bites without 2nd bit header, or less if the buffer
size has been set smaller).
The data are only valid after the rising edge of the CP bit in the bit header of the input buffer.
They remain valid until the falling edge of the CP bit, or until the controller issues a new job.
To adjust the read/write functions to the numerous possible applications, a few unique fea-
tures have been implemented that the user can select and set when parametering or program-
ming the processor. These are as follows:
If the Auto-Read function is activated, the data are read as soon as a data carrier is recog-
nized. No command from the controller is required. Since there is an in- and output buffer for
each read/write head, the start address must be specified for each head using the command
designator 07
Hex
. The start addresses may be different. The number of bytes read is deter-
mined by the selected size of the input buffer, which is distributed over both heads when 2 are
used.
This distinguishes the Auto-Read function from the standard setting for automatic reading,
which always starts at Address 0 and includes a maximum number of 30 bytes with 2nd bit
header or 31 bytes without 2nd bit header (or les if the buffer size has been set smaller).
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