Siemens MICROMASTER 420 - Page 65

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MICROMASTER 420 Reference Manual
Issue A1
57
3.3.12 Further advanced settings
The USS telegram can be customized for a particular application with the following
parameters (level 3 only).
P0003
= 3, allows access to expert parameters.
P2012
= USS PZD length.
The normal PZD length is 2 words as described earlier.
This parameter allows the user to choose a different length of PZD for control and
monitoring purposes.
For example a 3 word PZD would allow a second setpoint and actual value to be
used.
The second actual value could be set for example as the inverter output current (P2016
or P2019 index 3 =27).
P2013
= USS PKW length.
By default this is set to 127 (variable).
This means that the length of the PKW sent can be variable and also that the reply
telegram length will be variable.
This then affects the total length of the USS telegram.
If writing a control program, it may be useful to have a constant length telegram so
that, for example, the reply status word (ZSW) always occurs in the same position.
For MICROMASTER 420 the most useful PKW fixed length is 4 words as this allows
reading and writing of all parameters.
P2016
and
P2019:
These allow the user to define which status words and actual values are returned in the
reply PZD telegram for RS232 and RS485 respectively.
These are indexed parameters, which are set as follows:
Index 0 = status word 1 (ZSW) (default = 52 = inverter status word)
Index 1 = actual value 1 (HIW) (default = 21 = output frequency)
Index 2 = actual value 2(HIW2) (default = 0)
Index 3 = status word 2 (ZSW2) (default = 0)
3.3.13 Compatibility with previous MICROMASTER products
There are limitations to the compatibility between MICROMASTER 420 USS and
previous MICROMASTER products.
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The meaning of bits 11 and 12 have changed.
In order to get the motor to run right with MICROMASTER 420, bit 11 should be 0
(on MM3 it was 1).
To run left, bit 11 should be set to 1 (it was 0 on MM3 and bit 12 was 1).
i.e. The signal 047F(hex) will cause the inverter to run right and 0C7F(hex) will
cause the inverter to run left.