Cyclic Operation - Siemens SINUMERIK 840DiE sl Manual

01/2007
6.7.2

Cyclic operation

NC communication
Sign–of–life
monitoring
6.7.3 Monitor/control using the SIMATIC Manager
Monitoring and
controlling the
variable
© Siemens AG 2007 All Rights Reserved
SINUMERIK 840Di sl Manual (HBIsl) – 01/2007 Edition
In cyclic operation, communication or exchange of data and signals is carried
out between the PLC and the components NC, HMI (e.g. HMI Advanced) and
MCP (machine control panel).
The execution of the PLC program is carried out such that – with regard to time –
the basic PLC user program is executed prior to the PLC user program.
Communication of the PLC with the NC is carried out using the NC/PLC inter-
face. The interface is divided into the following areas:
S
Mode groups
S
Channels
S
Axes/spindles
S
General NC data
Data exchange through the NC/PLC interface is carried out in the basic PLC
program at the beginning of "OB1". This ensures that the data for the PLC re-
main constant over the entire PLC cycle.
The current G functions of the NC channels are transferred to the PLC (pro-
vided function is activated) on the process alarm level (OB40).
A cyclic, mutual sign–of–life monitoring function is activated between PLC and
NCK once power–up and the first OB1 cycle have been completed.
In case of failure of the PLC or in case of STOP of the PLC program execution,
the following alarm is displayed:
S
Interrupt: "2000 sign–of–life monitoring for PLC"
The SIMATIC Manager provides extensive functionality for testing the PLC pro-
gram or the module.
The menu command Target System > Monitor/Control Variable is used to
start the tool "Monitor/control variable".
The following functions can be performed with "Monitor/Control Variable":
S
Monitoring variables
Displaying the current value of individual variables of the PLC user program
or CPU module.
S
Controlling variables
Assigning values to variables of the PLC user program or CPU module.
6 PLC Commissioning
6.7 Testing the PLC program
6-157