Siemens S7-1200 System Manual page 695

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.
The following diagram shows the relationship of DONE, ERROR and STATUS parameters
when there is an error.
The DONE, ERROR and STATUS values are only valid until SEND_PTP executes again
with the same instance DB.
Table 12- 21 Condition codes
STATUS (W#16#....)
80D0
80D1
80D2
80D3
80D5
833A
S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG
Description
New request while transmitter active
Transmit aborted because of no CTS within wait time
Transmit aborted because of no DSR from the DCE device
Transmit aborted because of queue overflow (transmit more than 1024 bytes)
Reverse bias signal (wire break condition)
The DB for the BUFFER parameter does not exist.
Communication processor and Modbus TCP
12.3 Point-to-point (PtP) communication
695