Siemens S7-300 Manual page 19

Explanation of functioning in clocked mode
At Ti starts AD conversion for channel 7 and saves its result internally. Channels 6
to 0 are then converted sequentially in the same way at intervals of 52 ms. After an
additional internal processing time, the results of all the converted channels are
made available on the backplane bus to be picked up by the CPU.
Further information
You will find further information on clock synchronization in the online help system
of STEP 7, in the manual ET 200M Distributed I/O System and in the manual
Clock Synchronization.
Product Information on the Manual S7-300 Module Specifications, Edition 11/2002
A5E00213444-02
19