Siemens SIMATIC S7 System Manual page 542

105BCommunication processor
12.3 Point-to-Point (PtP) communication
Table 12- 20 Data types for the parameters
Parameter and type
REQ IN
PORT IN
BUFFER IN
LENGTH IN
PTRCL IN
DONE OUT
ERROR OUT
STATUS OUT
While a transmit operation is in progress, the DONE and ERROR outputs are FALSE. When
a transmit operation is complete, either the DONE or the ERROR output will be set TRUE to
show the status of the transmit operation. While DONE or ERROR is TRUE, the STATUS
output is valid.
The instruction returns a status of 16#7001 if the communication interface accepts the
transmit data. Subsequent SEND_PTP executions return 16#7002, if the CM or CB is still
busy transmitting. When the transmit operation is complete, the CM or CB returns the status
of the transmit operation as 16#0000 (if no errors occurred). Subsequent executions of
SEND_PTP with REQ low return a status of 16#7000 (not busy).
The following diagrams show the relationship of the output values to REQ. This assumes
that the instruction is called periodically to check for the status of the transmission process.
In the diagram below, it is assumed that the instruction is called every scan (represented by
the STATUS values).
The following diagram shows how the DONE and STATUS parameters are valid for only one
scan if the REQ line is pulsed (for one scan) to initiate the transmit operation.
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Data type Description
Bool Activates the requested transmission on the rising edge of this transmission
enable input. This initiates transfer of the contents of the buffer to the Point-to-
Point communication interface. (Default value: False)
PORT After you install and configure a CM or CB communication device, the port
identifier appears in the parameter helper drop-list available at the PORT box
connection. The assigned CM or CB port value is the device configuration
property "hardware identifier". The port symbolic name is assigned in the
"System constants" tab of the PLC tag table. (Default value: 0)
Variant This parameter points to the starting location of the transmit buffer. (Default
value: 0)
Note: Boolean data or Boolean arrays are not supported.
UInt Transmitted frame length in bytes (Default value: 0)
When transmitting a complex structure, always use a length of 0.
Bool This parameter selects the buffer as normal point-to-point or specific Siemens-
provided protocols that are implemented within the attached CM or CB.
(Default value: False)
FALSE = user program controlled point-to-point operations. (only valid option)
Bool TRUE for one scan, after the last request was completed with no error
Bool TRUE for one scan, after the last request was completed with an error
Word Execution condition code (Default value: 0)
S7-1200 Programmable controller
System Manual, 11/2011, A5E02486680-05