Siemens SIMATIC NET CP 243-1, Operating Instructions Manual

Page: 132 / 142

Sample program
CP 243-1
132
Operating Instructions, 03/2012, C79000-G8976-C244-02
Symbol Address Comment
Always_On
SM0.0 Due the system, always 1
ch_ready
MW8
cp_error
MW2
cp_ready
M0.0
ETH0_CTRL
SBR1 This POU was generated by the
Ethernet wizard for use with CP 243-1
NETWORK 2
As soon as channel 0 is ready for the transfer and "ch0_ready" is set, the "start" variable is
set. This may take several cycles.
LD ch0_ready
Sstart, 1
Symbol Address Comment
ch0_ready
M8.0 Bit for channel 0 in the CH_READY
return value of the ETH0_CTRL
subroutine
start
M4.0 Flip flop for automatic start of the data
transfer
NETWORK 3
For an S7-200, the "First_Scan_ON" bit is only set in the first cycle for system-related
reasons. This resets the "start" variable. This is necessary so that the "start" variable always
generates a signal edge for the start of the ETHx_XFR subroutine, even when the CPU
starts and stops repeatedly.
LD First_Scan_On
Rstart, 1
Symbol Address Comment
First_Scan_On
SM0.1 Due to the system, 1 in the first cycle,
otherwise always 0
start
M4.0 Flip flop for automatic start of the data
transfer
NETWORK 4
The local S7-200 station sends data from VB500 (data length of 5 bytes) via the Ethernet
connection to another S7-200 station. There the data is stored starting at VB500.