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Communications Capabilities
7.4.3
Use of the CP 523 in Communications Mode
Message frames of up to 256 bytes in length can be transferred between the CPU and a peripheral
device connected to the CP 523 module. The CP 523 offers you the following:
•
Communications with a terminal device (terminal, operator-process communication and visu-
alization units)
•
Point-to-point connection with another CP 523 or a CPU 944
You can choose between:
•
Transparent Communications mode
The CP 523 does not interpret any characters in Transparent Communications mode.
- No XON/XOFF protocol is possible.
- Messages can only be sent or received with a fixed length.
•
Interpretive Communications mode
The CP 523 evaluates the following characters in Interpretive Communications mode:
- RUB OUT (7F
)
H
- BACKSPACE (08
- XON/XOFF character (if programmed)
- Character end code (if programmed)
In Communications mode, the CPU initiates data exchange between the CPU and the CP by
sending a job request.
The CP 523 handles data transfer with the peripheral devices autonomously.
See the CP 523 Manual for a detailed description of the data exchange procedure.
The FB 252 BLUE function block integrated in the CPU 942-7UF12 allows user-friendly handling
and control of data exchange. See 7.4.5 for a description of FB 252 BLUE.
The time of day can be read from the integral clock by the CPU also in Communications mode and
used in the application program for date-dependent and time-dependent tasks.
Message text printout and editing as in Print mode is not possible in Communications mode. For
this reason, no memory submodule is required in Communications mode
7-44
)
H
S5-115F Manual
.
EWA 4NEB 811 6148-02
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