Siemens simatic et 200s Operating Instructions Manual page 323

Principle
What You Do
Provide the control interface with data corresponding to
the JOB.
Check the JOB_ACK feedback bit is at 0
Switch the JOB_REQ control bit from 1 to 0
Switch the JOB_REQ control bit from 1 to 0
Only when JOB_ACK = 0 can you activate a new JOB again.
Figure 7-6
ET 200S Positioning
Operating Instructions, 05/2007, A5E00124871-04
Response of the 1PosU
The 1PosU sets the feedback bit JOB_ACK = 1
This indicates that the initiation of the 1PosU has been detected
and that the JOB will be executed when JOB_ERR = 0.
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The JOB is not executed when JOB_ERR = 1.
The 1PosU sets the feedback bit JOB_ACK = 0
When a reference signal is evaluated, the 1PosU sets the
feedback bit SYNC = 1 when the function has been executed.
In the case of the latch function, the 1PosU sets the feedback bit
LATCH_DONE = 1 when the function has been executed.
Control and Feedback Signals with JOBs
In the case of the function for evaluating a reference signal,
the 1PosU sets the SYNC = 0 feedback bit at the same time.
In the case of the latch function, the 1PosU sets the
feedback bit LATCH_DONE = 0 at the same time.
All the other JOBs are thus executed.
1PosUniversal/Digital
7.6 Functions of the 1PosU
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