Delta Tau GEO PMAC Manual Do Utilizador

the format expected in that register.  If your SSI sensor is absolute over the entire travel of the motor, you 
will want to use Ix10 to configure your absolute position read.  If your SSI sensor is not absolute over the 
entire travel of the motor, leave Ix10 at the default value of 0 and establish your position reference with a 
homing search move. 

Ix10 consists of 6 hexadecimal digits.  The first two hex digits specify the format, and the last four hex 
digits specify the address of the source register.  Ix10 expects the source data to be in units of counts, so it 
must use the hardware input registers at Y:$FF54 and Y:$FF74. 

To read data from a Y-register, the first two hex digits simply specify the number of bits to be read as a 
hex number if the data is to be treated as an unsigned value, or as $80 plus the number of bits to be read if 
the data is to be treated as a signed value. 

The following table lists the values of Ix10 for the different possible SSI configurations: 

12-bit unsigned data 

$0CFF54 

$0CFF74 

12-bit signed data 

$8CFF54 

$8CFF74 

16-bit unsigned data 

$10FF54 

$10FF74 

16-bit signed data 

$90FF54 

$90FF74 

20-bit unsigned data 

$14FF54 

$14FF74 

20-bit signed data 

$94FF54 

$94FF74 

24-bit unsigned data 

$18FF54 

$18FF74 

24-bit signed data 

$98FF54 

$98FF74 

 

Ix83 specifies what register is to be read for the phase (commutation) position feedback every phase 
cycle.  It expects data in units of counts, and it expects a full 24 bits of position data (it cannot handle the 
rollover of data at less than 24 bits). 

If your SSI sensor is a full 24 bits and/or its data will never roll over (i.e. it is absolute over the full travel 
of the machine), you can read the SSI hardware input register here, setting Ix83 to $8FF54 to read 
Channel 1 or to $8FF74 to read Channel 2.  The “8” specifies that the source data is in a Y-register. 

However, if your SSI sensor provides less than 24 bits and it will roll over during operation (i.e. it is not 
absolute over the full travel of the machine), you will need to read instead the processed result of the 
conversion table for the sensor, which provides a full 24-bit rolled-over value.  In our example case where 
the result of the Channel 1 conversion is in X:$0722 and the result of the Channel 2 conversion is in 
X:$0725, Ix83 would be set to $0722 to use Channel 1 processed data, or to $0725 to use Channel 2 
processed data. 

In this case, however, note that the units of the result registers are 1/32-count, whereas Ix83 expects data 
in units of counts.  This means that you will need to specify your commutation cycle size with Ix70 and 
Ix71 as 32 times bigger than it would normally be. 

Ix81 specifies what register is to be read for the phase (commutation) position feedback on power-on to 
establish the absolute rotor angle for a synchronous motor such as a permanent-magnet brushless servo 
motor, and what format that data is in.  Virtually all SSI encoders are absolute over one motor revolution, 
so Ix81 will almost always be used in this case. 

Ix81 consists of 6 hexadecimal digits.  The first two hex digits specify the format, and the last four hex