Siemens SIMATIC CM35, Руководство пользователя

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6-10
CM35 Counter Module
(4) J31069-D0416-U001-A5-7618
6.6 Reading the Measured Values
You can read the current measuring values of the CM35 in ² period duration
measurement ² mode.
To ensure data consistency, the read access must be performed with one load
command (L PIW).
When an overflow occurs, the hex value FFFDH (65533) is transferred (fre-
quency below the minimum frequency, encoder interrupted, and so on).
Measuring channels which have not yet been started are transferred with the
value 0000H regardless of whether or not pulses are present on the input.
Table 6-8 shows the addresses of the individual channels for reading the mea-
sured value.
Table 6-8 Assignment of the output area for reading the measured values
Offset to the
Module Start Address
Meaning Value Range
+0 Period duration average value, chan. 1 0 to 65532
+2 Period duration average value, chan. 2
+4 Period duration average value, chan. 3
+6 Period duration average value, chan. 4
+8 Period duration average value, chan. 5
+10 Period duration average value, chan. 6
+12 Period duration average value, chan. 7
+14 Period duration average value, chan. 8
Example: ² Period duration measurement ² mode
-- Read the measured value of channel 2
-- The CM35 has the module start address 256.
L PIW 258 // Address = 256 + 2, measured value
channel 2
T MW16 // Save the counting value
Period Duration Measurement Operating Mode