CP 523
Technical Description
Data transfer between the CP and peripheral device takes place as follows:
The CP 523 sets the "DTR" output after startup. This indicates that the CP is operable and ready to
receive.
Example:
The CP wants to send data
1.
CP waits till DSR = ON
If the peripheral device still has not set DSR to ON after 20 s, the CP reports the error to the
CPU (peripheral device not ready).
2.
CP sets RTS
3.
CP waits till CTS = ON
If the peripheral device still has not set CTS to ON after 20 ms, the CP reports the error to the
CPU (peripheral device not ready).
4.
CP sends data
5.
CP resets RTS after sending data
6.
Peripheral device sets CTS to OFF
Figure 2-5. Timing Diagram for Data Transfer between the CP and the Peripheral Device
XXXXXXXX
XXXXXXXX
XXXXXXXX
RXD
TXD
DTR
RTS
DSR
CTS
1
0
CP switched
on
max:
20 s
.
Peripheral device switched on
max:
20 s
.
CP reports data
cannot be received
ON
OFF
ON
OFF
1
0
ON
OFF
ON
OFF
XXXXXXXX
Example:
Peripheral device wants to send data
The peripheral device only checks the DTR line
If ON: Data may be sent (CP ready to receive)
If OFF: Data transmission must be interrupted (CP not ready to receive)
EWA 4NEB 811 6044-02a
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