Siemens SIMATIC NET CP 243-1, Operating Instructions Manual

Page: 97 / 142

Programming
4.3 ETHx_XFR
CP 243-1
Operating Instructions, 03/2012, C79000-G8976-C244-02
97
Return parameters
Name Type Meaning
Done BOOL Status of the subroutine call
0: Subroutine not executed yet
1: Subroutine executed, ready for next
execution
Error BYTE Error code
16#00: No error occurred
Otherwise: Error (description: see
section Error messages of the CP 243-
1 (Page 108))
Return parameters (ETHx_CFG)
4.3 ETHx_XFR
Calling the subroutine ETHx_XFR causes the CP 243-1 to transfer data to or request data
from another S7 system. The type of data access that your CP 243-1 uses is specified in the
configuration. This means that you have already specified the following during configuration:
●
What data is to be accessed.
● Whether the data is to be read or written.
● The communications partner from which this data is obtained or to which this data is
transferred.
When you call the ETHx_XFR subroutine, you specify which of the configured client
channels you want to use for which configured data accesses.
The ETHx_XFR subroutine is only created by the Internet wizard in STEP 7 Micro/WIN 32 if
you have configured at least one of the channels of the CP 243-1 as client. Only then can
you trigger data access from a S7-200 user program via a CP 243-1.
Only one ETHx_XFR subroutine per channel can be active at any one time. Parallel
execution of several data accesses to one channel is impossible. As a result, it is advisable
to link the "START" input with both the return value "Done" of the ETHx_XFR subroutine and
the corresponding bit of the return value "CH_Ready" from the ETHx_CTRL subroutine.