Reference Manual

Turbo PMAC/PMAC2 Software Reference
Turbo PMAC Global I-Variables 87
bits of fractional data). The result registers in the Encoder Conversion Table are located at addresses
X:$003501 to X:$0035C0, corresponding to table setup I-variables I8000 to I8191, respectively.
For a control-loop with only a single feedback device – the usual case – Ixx03 and Ixx04 will have the
same value, so the same register is used for both position and velocity loops. For a control loop with dual
feedback, motor and load, use Ixx03 to point to the encoder on the load for the position loop, and Ixx04 to
point to the encoder on the motor for the velocity loop. If the velocity loop uses feedback with different
resolution from the position loop, the Ixx09 velocity-loop scale factor should be different from the Ixx08
position-loop scale factor.
Ixx05 Motor xx Master Position Address
Range: $000000 - $FFFFFF
Units: Turbo PMAC ‘X’ Addresses
Default: $0035C0 (end of conversion table)
WARNING:
Never use the same register for master position and feedback position for the same
motor. A dangerous runaway condition may result.
Ixx05 specifies the address of the register for master position information of Motor xx for the position
following, or electronic gearing, function. Typically, this is a register in the encoder conversion table
(addresses $003501 to $0035C0), where processed input position data resides.
The position following function is only enabled if Ixx06 is set to 1 or 3.
Ixx06 Motor xx Position Following Enable and Mode
Range: 0 - 3
Units: none
Default: 0
Ixx06 controls the position following function for Motor xx. It determines whether following is enabled
or disabled, and whether the following function is in normal mode or offset (superimpose) mode.
Normal Mode: In normal following mode, motor position changes due to following are reported when
the motor position is queried, and subsequent programmed moves for the motor cancel out the position
changes due to the following function.
Offset Mode: In offset following mode, motor position changes due to following are not reported when
the motor position is queried (the position reference is effectively offset for the motor), and subsequent
programmed moves are added on top of the position changes due to the following function. This permits
the superimposition of programmed and following moves in offset mode.
Ixx06 is a two-bit value. Bit 0 controls the enabling of the following function (0 = disabled, 1 = enabled).
Bit 1 controls the following mode (0 = normal mode, 1 = offset mode). This yields four possible values
for Ixx06:
 Ixx06 = 0: Following disabled, normal mode
 Ixx06 = 1: Following enabled, normal mode
 Ixx06 = 2: Following disabled, offset mode
 Ixx06 = 3: Following enabled, offset mode
Note:
The following mode can be important even when following is disabled, because it
affects how subsequent programmed moves are calculated. If the following mode
is ever changed, a PMATCH position-matching command must be executed before
the next programmed move is calculated. Otherwise, that move will use the wrong