The encoder turns three revolutions per one revolution of the motor shaft.
• 90.51 = Encoder 2
The line speed measured by encoder 2 can be read from 90.3. This value is given
in rpm which can be converted into another unit by using 90.53 and 90.54. Note
that the feed constant gear cannot be used in this conversion because it does not
affect 90.3.
Example 3: ACS 600 / ACS800 compatibility
With ACS 600 and ACS800 drives, both the rising and falling edges from encoder
channels A and B are typically counted to achieve best possible accuracy. Thus the
received pulse number per revolution equals four times the nominal pulse number
of the encoder.
In this example, an HTL-type 2048-pulse encoder is fitted directly on the motor
shaft. The desired initial position to correspond the proximity switch is 66770.
In the ACS880, the following settings are made:
• 92.1 = HTL
• 92.2 = Module 1
• 92.10 = 2048
• 92.13 = Enable
• 90.51 = Encoder 1
• 90.63 = 8192 (ie. 4 × value of 92.10, as the received number of pulses is 4 times
nominal. See also parameter 92.12)
• The desired “data out” parameter is set to Other – 90.58 (32-bit format). Only
the high word needs to be specified – the subsequent data word is reserved
for the low word automatically.
• The desired sources (such as digital inputs or user bits of the control word)
are selected in 90.67 and 90.69.
In the PLC, if the initial value is set in 32-bit format using low and high words
(corresponding to ACS800 parameters POS COUNT INIT LO and POS COUNT INIT
HI), enter the value 66770 into these words as follows:
• Eg. PROFIBUS:
• FBA data out x = POS COUNT INIT HI = 1 (as bit 16 equals 65536)
• FBA data out (x + 1) = POS COUNT INIT LO = 1234.
• ABB Automation using DDCS communication, eg.:
• Data set 12.1 = POS COUNT INIT HI
• Data set 12.2 = POS COUNT INIT LO
To test the configuration of the PLC, initialize the position counter with the encoder
connected. The initial value sent from the PLC should immediately be reflected by
98 Program features
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