7
7
english
Application
BIS L-405-... Processor
Signal description
Tag Present (TP):
Indicates a data carrier in the field.
Address (ADR):
Signal change outputs the next data carrier address.
Strobe (STR):
This signal acknowledges the data output on the parallel interface.
ReStart:
Deletes the data memory in the BIS L-405 and sets all data outputs to
0. The data carrier is then read again or, if no data carrier is present,
only the data outputs are set to 0. This signal is also used to turn off
the read antenna. If two read heads are installed close together and
interfere with each other, this can deactivate one read head as long as
the other needs to be available.
D0..D7:
Data outputs
When supply voltage is applied, the data outputs are in an undefined state for approx.
100 ms. Then they switch to 0. The first byte cannot be read until the ADR signal changes.
BIS L-405-03_-00_-05-MU_834487_E_0709.p65
8
english
8
Application
BIS L-405-... Processor
Timing
Read 5 bytes
Detection of a new data carrier is indicated by the TP signal. The first data value is not
output until the ADR input signal changes. Each time ADR changes, the value of the next
address is given to the data outputs. As an acknowledgement of the data change, the
processor invertes the STR signal. Once the last byte is output, a change in ADR is
followed by a data value output of 0. Any further change to ADR does result in a change to
the STR signal, but the data remain 0. This is how the end of data can be recognized.
If the data carrier leaves the read head before all the data have been output, the data
remain stored for a subsequent data read. Before a new data carrier is recognized by the
read head, data transmission must have been completed.
If the next data carrier enters the read zone before the data have been picked up, the "Tag
Present" (Overflow) LED will indicate this by flashing. The data from the new tag are not
output, and a ReStart must be performed to resynchronize.
tx
tx
t1
t1
t1
t1
t1
t2
t2
t2
t2
t2
t2
Data value = 0
Byte 0
Byte 1
Byte 3
Byte 4
Data value = 0
Data carrier
TP
ADR
Data
STR
tx = Read time
≈
140 ms t1 = Data output before Strobe
≈
6 ms
t2 = Response to address change
≤
15 ms