Siemens SIMATIC S7-1500 Manual page 39

Configuring/address space
4.1 Operating with "Counting and measurement" technology object
Parameter
Measured variable
Update time [ms] of meas-
uring function
Time base for velocity
measurement
Increments per unit
NOTICE
Too high an encoder speed can supply the wrong rotation direction
If an SSI absolute encoder rotates so fast that more than half the value range is covered
within one module cycle
correctly. As a result, the following may function incorrectly:
• DQ functions
• Feedback bits EVENT_OFLW, EVENT_UFLW, EVENT_ZERO, EVENT_CMP0,
Non-isochronous mode: 500 μs; isochronous mode: PROFINET cycle time
1
Note
If you use an SSI absolute encoder whose value range does not correspond to a power of 2,
the calculated velocity measurement can be incorrect at the moment of the overflow.
Explanation of parameters
You can find a detailed description of the parameters in function manual Counting,
Measurement and Position Detection in sections Basic parameters and Configuring the
SSI_Absolute_Encoder available for download on the Internet
(http://support.automation.siemens.com/WW/view/en/59709820).
38
Value range
Frequency
•
Period
•
Velocity
•
Complete SSI frame
•
0...25000
1 ms
•
10 ms
•
100 ms
•
1 s
•
60 s
•
1...65535
, the velocity and rotation direction are no longer calculated
1
EVENT_CMP1 and STS_DIR
Default setting Parameter
reassign-
Frequency Yes
10 Yes
60 s Yes
1 Yes
Technology module TM PosInput 2 (6ES7551-1AB00-0AB0)
Scope
HSP for STEP 7
ment in
(TIA Portal)
RUN
Channel
Channel
Channel
Channel
Manual, 06/2018, A5E03982218-AB