P4: PLC for SINUMERIK 828D
14.4 Test and diagnostic functions
Basic Functions
1132 Function Manual, 09/2011, 6FC5397-0BP40-2BA0
14.4.1.2 Preconditions of the status update
Before you can update the status to monitor and test your program, you must execute the following tasks:
• Your program must be able to be compiled error-free.
• You must have set-up the communication between the Programming Tool PLC828 and the target system.
• Your program must have been loaded error-free into the target system.
• After you have loaded the program into the target system, then you should again bring this into the RUN
operating state. Otherwise, the address status is displayed, however, the target system cannot execute the
program so that you are not shown the logic operations that you expect.
14.4.1.3 Influence of the operating state on the target system
The type of monitoring and test functions that you execute depends on the operating state of your target system.
Even if your program is not executed in the STOP operating state, the operating system of the target system still
monitors the target system (status of RAM and I/O, and transfers the data status to the Programming Tool
PLC828. If the target system is in the STOP operating state, then you can execute the following functions:
• You can display the actual values of the addresses in the table status or in the program status. (This is the
same as the function "Single read", as the program is not executed.)
• You can write values in the table status.
• You can execute a certain number of cycles and display the effect in a status chart and/or in the program
status.
If the target system is in the RUN operating state, you cannot execute the functions "First cycle" or "Several
cycles". You can write values into a status chart, you can also execute the following functions (not in the STOP
operating state):
• In the table status, you can carry out the continuous updates. (If you wish to only execute an update, you must
switch-off the table status so that you can execute the command "Single read".)
• You can execute continuous updates in the program status.
14.4.1.4 Communication and cycle
In a continuous cycle, the target system reads the inputs, it executes the program, writes to the outputs and
executes system functions as well as the communication. This cycle runs with an extremely high speed of many
times per second. Even if the Programming Tool PLC828 issues status requests in a fast sequence, it is
important that you clearly understand that you cannot monitor each individual event that takes place in the target
system. When using the program status or the table status, if you read data values from a target system program,
the interrogate the data by taking samples (spot check). The update rate of the status values read from the target
system depends on the communication baud rate.
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