Clocked Mode - Siemens SIMATIC ET 200S Operating Instructions Manual

1Count5V
3.2 Isochronous mode
3.2 Isochronous mode
Note
For basic information on isochronous mode, refer to the Isochronous mode
(http://support.automation.siemens.com/WW/view/en/15218045) function manual.
Hardware Requirements
You will require the following for the 1Count5V in isochronous mode:
● A CPU that supports isochronous mode
● PROFIBUS master or PROFINET controller that supports the constant bus cycle time
● An IM 151 that supports isochronous mode
Features
Depending on the system parameter assignment, the 1Count5V/500kHz works in either non-
isochronous or isochronous mode.
In isochronous mode, data communication between the master and 1Count5V is
isochronous to the bus cycle (PROFIBUS DP/PROFINET).
In isochronous mode, all 8 bytes / 12 bytes of the feedback interface are consistent.
If a parameter assignment error occurs, the 1Count5V does not go into isochronous mode.
If isochronous mode fails due to faults or failure/delay of global control (GC), the 1Count5V
returns to isochronous mode during the next cycle without an error response.
If isochronous mode fails, the feedback interface is not updated.
The T
See also
Synchronization (Page 143)
122
/T overlap is supported by the module in firmware version V1.0.1 and later.
i o
Technological Functions
Operating Instructions, 06/2010, A5E00124867-07