Delta Tau PBC Series, Hardware Reference Manual

Page: 187 / 207

Power Brick Controller User Manual
Special Functions & Troubleshooting 187
Encoder Count Error
The Power Brick Controller is fitted with an encoder count error detection circuitry which supports
Quadrature , Sinusoidal , Resolver , and HiperFace encoders.
The encoder count circuitry reports bad transitions of the quadrature signals. If both the A and B channels
of the quadrature data change state at the decode circuitry (post-filter) in the same hardware sampling clock
cycle,
an unrecoverable error to the counter value will result (lost counts).
PowerBrick[].Chan[].CountError is then set and latched to 1 (until reset or cleared). 0 indicates that there
is no encoder count error.
Note
No automatic action is taken by the Power Brick Controller if the
encoder count error bit is set, it is the user’s responsibility to trap it
and create safety logic to stop the machine and / or alert the operator.
The encoder count error may not have immediate consequences on the motion, but it indicates ultimately
that the motor is losing counts which could result in a fatal following error, erroneous commutation, or
position drift over time.
Common root causes of the encoder count error:

Encoder problem


Trying to move the encoder (motor) faster than it’s specification


Using a higher resolution/speed encoder. This may require increasing the sampling clock.

The default sampling clock of ~3.125 MHz is
acceptable for the majority of applications.
Increasing the encoder sampling clock is done using
the structure element
PowerBrick[].EncClockDiv (default = 5).
Setting Frequency
0 100 MHz
1 50 MHz
2 25 MHz
3 12.5 MHz
4 6.25 MHz
5 3.125 MHz
6 1.562 MHz
7 781.2 kHz
Setting Frequency
8 390.6 kHz
9 195.3 kHz
10 97.65 kHz
11 48.82 kHz
12 24.41 kHz
13 12.21 kHz
14 3.104 kHz
15 3.052 kHz
PTR Enc1CountError->PowerBrick[ 0 ].Chan[ 0 ].CountError;
PTR Enc2CountError->PowerBrick[ 0 ].Chan[ 1 ].CountError;
PTR Enc3CountError->PowerBrick[ 0 ].Chan[ 2 ].CountError;
PTR Enc4CountError->PowerBrick[ 0 ].Chan[ 3 ].CountError;
PTR Enc5CountError->PowerBrick[ 1 ].Chan[ 0 ].CountError;
PTR Enc6CountError->PowerBrick[ 1 ].Chan[ 1 ].CountError;
PTR Enc7CountError->PowerBrick[ 1 ].Chan[ 2 ].CountError;
PTR Enc8CountError->PowerBrick[ 1 ].Chan[ 3 ].CountError;