Glossary
CPU 1516pro-2 PN (6ES7516-2PN00-0AB0)
134 Operating Instructions, 09/2016, A5E35873416-AA
Counters are components of the system memory of the CPU. You can modify the content of
the "counter cells" using STEP 7 instructions (e.g. count up/down).
The CPU uses the integrated system power supply to supply the electronics of the modules
via the backplane bus. The CPU contains the operating system and executes the user
program. The user program is located on the SIMATICmemory card and is processed in the
work memory of the CPU. The PROFINET interfaces on the CPU allow simultaneous
communication with PROFINET devices, PROFINET controllers, HMI devices, programming
devices, other controllers and other systems.
The cycle time represents the time a CPU requires to execute the user program once.
see "Interrupt, cyclic"
Data blocks (DBs) are data areas in the user program that contain user data. There are
global data blocks, which can be accessed from all code blocks, and instance data blocks,
which are assigned to a specific FB call.
A device can send, receive or amplify data via the bus, e.g. IO device via PROFINET IO.
Before an IO device can be addressed by an IO controller, the IO device requires a device
name. PROFINET uses this approach because names are easier to handle than complex IP
addresses.
In its delivery state, an IO device has no device name. An IO device can only be addressed
by an IO controller - e.g., for transferring configuration data (including the IP address) during
startup, or for user data exchange during cyclic operation - after it has been assigned a
device name with the programming device/PC.
The diagnostic buffer is a battery-backed memory area in the CPU where diagnostic events
are stored in their order of occurrence.
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