Siemens Simatic S7-300 CP 341 User Manual page 211

Description of FC 22 (RECEIVE)
Program section "Enable receive data":
In order to receive data, the P_RCV_RK EN_R receive enable at the P_RCV_RK block must
be set to 1.
Program section "P_RCV_RK NDR=1":
If P_RCV_RK NDR is set, it means that new data has been received and the receive counter
P_RCV_RK COUNTER_OK is incremented.
Program section "P_RCV_RK ERROR=1":
If an error occurs, i.e., the error bit at the parameter output of P_RCV_RK is set, the
P_RCV_RK COUNTER_ERR error counter is incremented. In addition, P_RCV_RK STATUS
is copied, since it will be overwritten with 0 during the next cycle, making it impossible to
read it out.
All relevant values can be monitored in the VAT for testing purposes.
Description "CP341 V24"
● The "read and control RS 232C accompanying signals" functions can only be carried out
with the ASCII driver. Control is only possible if you have not set the "Automat. control of
V24 signals" parameter on the "Transfer" tab.
● The V24 signals can be read and written using the variable table. The signal states
SET_DTR and SET_RTS can be preselected by means of memory bits M 1.6 and M 1.7.
When the signal at I 0.7 changes from "0" to "1", this state is transferred to the CP by the
FC V24_SET function.
● The FC V24_STAT function is called cyclically. The status of the CP 341 V24 signals can
be read out via memory bits 3.0 to 3.5.
CP 341 Point-to-Point Communication, Installation and Parameter Assignment
Manual, 09/2008, A5E02191071-01
www.gkbpx.com
Programming Example for Standard Function Blocks
9.6 Activation, Start-Up Program and Cyclic Program
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