Delta Tau GEO BRICK LV Reference Manual
Turbo PMAC/PMAC2 Software Reference
Turbo PMAC Global I-Variables
206
I68n3 and I69n3 determine which of the Flag inputs will be used for hardware position capture (if one is
used) of the encoder counter of Channel n* (n* = 1 to 2) on a DSPGATE2 MACRO IC. For MACRO
ICs 0 and 2, n = n*; for MACRO ICs 1 and 3, n = n* + 5 (i.e. I6813 controls MACRO IC 0 Channel 1;
I6973 controls MACRO IC 3 Channel 2). I68n2/I69n2 determines whether a flag is used and which
polarity of the flag will cause the trigger. The possible values of I68n3/I69n3 and the flag each selects is:
used) of the encoder counter of Channel n* (n* = 1 to 2) on a DSPGATE2 MACRO IC. For MACRO
ICs 0 and 2, n = n*; for MACRO ICs 1 and 3, n = n* + 5 (i.e. I6813 controls MACRO IC 0 Channel 1;
I6973 controls MACRO IC 3 Channel 2). I68n2/I69n2 determines whether a flag is used and which
polarity of the flag will cause the trigger. The possible values of I68n3/I69n3 and the flag each selects is:
I68n3/I69n3 = 0: HOMEn (Home Flag n)
I68n3/I69n3 = 1: PLIMn (Positive End Limit Flag n)
I68n3/I69n3 = 2: MLIMn (Negative End Limit Flag n)
I68n3/I69n3 = 3: USERn (User Flag n)
I68n3/I69n3 is typically set to 0 for homing search moves in order to use the home flag for the channel.
Typically, it is set to 3 afterwards to select the User flag if other uses of the hardware position capture
function are desired, such as for probing and registration. To capture on the PLIMn or MLIMn overtravel
limit flags, disable their normal functions with Ixx25 or use a channel n where none of the flags is used
for the normal axis functions.
Typically, it is set to 3 afterwards to select the User flag if other uses of the hardware position capture
function are desired, such as for probing and registration. To capture on the PLIMn or MLIMn overtravel
limit flags, disable their normal functions with Ixx25 or use a channel n where none of the flags is used
for the normal axis functions.
Note:
By default, the flag inputs of MACRO IC 0 are not used on a Turbo PMAC2.
I68n4/I69n4 MACRO IC Channel n* Encoder Gated Index Select
Range:
0 - 1
Units:
none
Default:
0
Note:
This I-variable is only active if the MACRO IC is present, and is a DSPGATE2 IC.
The presence and type of MACRO ICs are reported in I4902 and I4903.
The presence and type of MACRO ICs are reported in I4902 and I4903.
I68n4 and I69n4 control whether the raw encoder index channel input or a version of the input gated by
the AB-quadrature state is used for position capture of the encoder counter of Channel n* (n* = 1 to 2) on
a DSPGATE2 MACRO IC. For MACRO ICs 0 and 2, n = n*; for MACRO ICs 1 and 3, n = n* + 5 (i.e.
I6814 controls MACRO IC 0 Channel 1; I6974 controls MACRO IC 3 Channel 2). They have the
following possible settings:
the AB-quadrature state is used for position capture of the encoder counter of Channel n* (n* = 1 to 2) on
a DSPGATE2 MACRO IC. For MACRO ICs 0 and 2, n = n*; for MACRO ICs 1 and 3, n = n* + 5 (i.e.
I6814 controls MACRO IC 0 Channel 1; I6974 controls MACRO IC 3 Channel 2). They have the
following possible settings:
I68n4/I69n4 = 0: Use ungated index for encoder position capture
I68n4/I69n4 = 1: Use index gated by quadrature channels for position capture
When I68n4/I69n4 is set to 0, the encoder index channel input (CHCn) is passed directly into the position
capture circuitry.
capture circuitry.
When I68n4/I69n4 is set to 1, the encoder index channel input (CHCn) is logically combined with (gated
by) the quadrature signals of Encoder n before going to the position capture circuitry. The intent is to get
a gated index signal exactly one quadrature state wide. This provides a more accurate and repeatable
capture, and makes the use of the capture function to confirm the proper number of counts per revolution
very straightforward.
by) the quadrature signals of Encoder n before going to the position capture circuitry. The intent is to get
a gated index signal exactly one quadrature state wide. This provides a more accurate and repeatable
capture, and makes the use of the capture function to confirm the proper number of counts per revolution
very straightforward.
In order for the gated index capture to work reliably, the index pulse must reliably span one, but only one,
high-high or low-low AB quadrature state of the encoder. I68n5/I69n5 allows the selection of which of
these two possibilities is used.
high-high or low-low AB quadrature state of the encoder. I68n5/I69n5 allows the selection of which of
these two possibilities is used.
Note:
If I68n4/I69n4 is set to 1, but I68n2/I69n2 bit 0 is set to 0, so the index is not used
in the position capture, then the encoder position is captured on the first edge of
any of the U, V, or W flag inputs for the channel. In this case, bits 0, 1, and 2 of
the channel status word tell what hall-state edge caused the capture.
in the position capture, then the encoder position is captured on the first edge of
any of the U, V, or W flag inputs for the channel. In this case, bits 0, 1, and 2 of
the channel status word tell what hall-state edge caused the capture.