Siemens SIMATIC FM 452, Manual

Page: 115 / 210

Settings
9-17
FM 452 Electronic Cam Controller
C79000-G7076-C452-04
Data Used in the Channel DB
Address Name Type Initial Value Comment
25.1 MSR_DONE BOOL FALSE 1 = length measurement completed
34.0 EDGE_ON BOOL FALSE 1 = edge detection on
34.2 MSR_ON BOOL FALSE 1 = length measurement on
38.2 MSRRD_EN BOOL FALSE 1 = read measured values
112.0 BEG_VAL DINT L#0 Start value
116.0 END_VAL DINT L#0 End value
120.0 LEN_VAL DINT L#0 Length
Data Used in the Parameter DB
Address Name Type Initial Value Comment
4.0 EDGEDIST DINT L#0 Minimum edge-to-edge distance for edge
detection
Range:
0 ... 1 000 000 000 m
With the minimum edge-to-edge distance, you define a range after detection of the start of measurement
when using edge acquisition. If the end of the measurement is within this range, the measurement is
rejected.
The start of the measurement is signaled only after the minimum edge-to-edge distance has been
traveled.
Conditions for Length Measurement
•
The distance between the off edge and on edge at input I1 must be large
enough so that your program on the CPU can evaluate the measurement result
correctly before a new measurement begins.
•
The minimum interval between the rising and the falling edge at input I1 as well
as between the falling and the next rising edge at input I1 must be greater than
2 ms.
Hardware Interrupts
The start and end of a measurement can be signaled by hardware interrupts
(see Section 6.1, page 6-2).