Rules
You can use the time stamping for selected input signals and for input signals that are important
for your application. On an ET 200PA SMART, the input signals of a maximum of 128 digital
inputs can be time stamped. For a better load distribution on the PROFIBUS DP and in the
IM 650, we recommend distributing these signals if necessary over several ET 200PA SMART
stations.
The IM 650 interface module supports time stamping of input signals of a maximum of 32 digital
inputs per slot. The existing limit of a maximum of 128 time-stamped channels (DI) per
ET 200PA SMART is retained.
You can use the following digital input modules from the S7-300 series of modules for the time
stamping:
● 6ES7321-7EH00-0AB0 (1 ms)
● 6ES7321-7TH00-0AB0 (10 ms)
● 6ES7321-7RD00-0AB0 (10 ms)
The figures shown in brackets specify the maximum possible accuracy. Also observe the
installation guidelines for the respective accuracy class.
Limit conditions
The accuracy of the time stamping is influenced by the following limit conditions:
● The number of modules used in the station affects the accuracy of the time stamping, that
is, a maximum accuracy of 1 ms is possible with up to 8 modules and a maximum accuracy
of 10 ms with up to 12 modules.
● The number of time-stamped input signals in an ET 200PA SMART affects the accuracy of
the time stamping, that is, more time-stamped input signals reduce the accuracy of the time
stamping.
● Process interrupts as well as reading/writing of data records reduce the accuracy of the time
stamping.
The specified accuracies for the time stamping (10 ms or 1 ms) will, however, always be
adhered to.
Operating principle
The IM 650 provides changed input signals with the respective current time and saves these in
a buffer (message list). Such a message list is a data record with a maximum of 20 messages
about time-stamped signal changes. The IM 650 can store up to 15 data records.
A signal message provides the following information:
● Slot number of the (signaling) DI module (4 ... 15)
● Channel number of the DI module
● Signal state (incoming, outgoing)
● Time of the signal change
When there are time-stamped signals or a data record is full, the IM 650 generates a hardware
interrupt to the DP master. The buffer can be evaluated, for example, with "Read data record".
Functions
7.4 Time stamping of the input signals with IM 650
ET 200PA SMART
74 Operating Instructions, 06/2019, A5E34192013-AB
To Next Page
Loading...
Need help?
General
