Siemens SIMATIC S5-115U, User Manual

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S5-115U Manual Integral Blocks
The RECEIVE block must be called in the control program in "ALL" mode at least once per inter-
face when
•
the CP wants to give data to the PLC on its own initiative.
• the amount of data to be received with RECEIVE DIRECT exceeds the specified frame size.
• the CP uses RECEIVE DIRECT only to enable receive data, and transfers data to the PLC via
"background communications".
You can call FB245 in RECEIVE ALL mode in
•
the cyclic program (e.g., in OB1)
• the service routine for timed interrupts (e.g. prompter block)
• the service routine for process interrupts
Description of the RECEIVE DIRECT Function
The RECEIVE DIRECT function works with the following parameters:
•
SSNR - interface number
• A-NR - job number (assign " 0")
• ANZW - job status word
• PAFE - parameter assignment error byte
• ZTYP - destination type
• DBNR - data block number
• ZANF - destination start address
• ZLAE - amount of destination data
Normally, the RECEIVE DIRECT function is called in the cyclic part of the control program. This
block can also be called in an interrupt service routine, but the job status word is not updated
cyclically in this case. The CONTROL block must then perform this task.
The RECEIVE block communicates with the CP on a handshaking basis under the following con-
ditions only:
•
RLO "1" has been forwarded to the function block.
• The CP has enabled the job. (The "RECEIVE ready" bit in the job status word is set).
When RLO "0" is forwarded, only the job status word is updated.
If "NN" is assigned to the ZTYP parameter, the CP must provide the destination parameters.
Otherwise, the job is aborted with an error.
If the CP provides the destination parameters, when ZTYP is not "NN", only the parameter specifi-
cations in the block are noted.
Large amounts of data can be received in the form of frames only. Only one data frame can be
received at a time with RECEIVE DIRECT. The remaining data or additional data frames must
therefore be transferred to the PLC with RECEIVE ALL.
EWA 4NEB 811 6130-02b
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