Delta Tau GEO BRICK LV User Manual
Turbo PMAC User Manual
240
Turbo PMAC Computational Features
P72=(M72-P69*M71)/(M70*P70)
; Servo task duty cycle
P68=INT((M71+M72+M73)/M70)
; # of times phase interrupted RTI
P67=INT((M71+M72+M73)/(M70*P70))
; # of times servo interrupted RTI
P73=(M73-P68*M71-P67*(M72-P69*M71))/(M70*P70*(I8+1))
;
;
RTI
task
duty
cycle
P74=P71+P72+P73
; Latest total foreground duty cycle
P75=(P75*(P76-1)+P74)/P76
; Averaged total foreground duty cycle
CLOSE
Background Cycle Time
There are two timer registers important to evaluate the time required to execute a background cycle.
These registers are involved in the operation of the watchdog timer. The register at address Y:$000025 is
set to the value of I40 at the end of every background cycle. (If I40 is 0, the register is set to 4095.) Until
the next background cycle is completed, this register is decremented every servo cycle. The data
gathering function is useful to establish how long background cycles take.
These registers are involved in the operation of the watchdog timer. The register at address Y:$000025 is
set to the value of I40 at the end of every background cycle. (If I40 is 0, the register is set to 4095.) Until
the next background cycle is completed, this register is decremented every servo cycle. The data
gathering function is useful to establish how long background cycles take.
The register at X:$000025 contains the lowest value reached by Y:$000025 since the last power-up/reset
of the Turbo PMAC. If this is close to 0, the Turbo PMAC has come close to tripping its watchdog timer,
and background tasks such as PLC program execution, communications response, and safety checks have
been slow.
of the Turbo PMAC. If this is close to 0, the Turbo PMAC has come close to tripping its watchdog timer,
and background tasks such as PLC program execution, communications response, and safety checks have
been slow.
Numerical Values
Turbo PMAC can store and process numerical values in many forms, with both fixed-point and floating-
point values. The Motorola 56300 DSP that acts as Turbo PMAC’s CPU is a fixed-point processor with
built-in 24-bit and 48-bit arithmetic capability (plus a 56-bit accumulator). However, Turbo PMAC’s
firmware implements a full set of floating-point routines.
point values. The Motorola 56300 DSP that acts as Turbo PMAC’s CPU is a fixed-point processor with
built-in 24-bit and 48-bit arithmetic capability (plus a 56-bit accumulator). However, Turbo PMAC’s
firmware implements a full set of floating-point routines.
Internal Formats
The internal servo, interpolation, and commutation routines all operate with fixed-point arithmetic, 24-bit
and 48-bit, for maximum speed. The user programs, motion and PLC, use 48-bit floating-point arithmetic
for maximum range and generality. Even when reading from and/or writing to fixed-point registers, the
intermediate formats are all floating-point values. This permits users to mix different variable types at
will, letting Turbo PMAC handle the type matching automatically
and 48-bit, for maximum speed. The user programs, motion and PLC, use 48-bit floating-point arithmetic
for maximum range and generality. Even when reading from and/or writing to fixed-point registers, the
intermediate formats are all floating-point values. This permits users to mix different variable types at
will, letting Turbo PMAC handle the type matching automatically
The only exception to this rule is the compiled PLC programs; in a statement containing only “L-
variables” and integer constants that can fit in a signed 24-bit range (+/-8M), the intermediate format is
signed 24-bit integer. Refer to the section on compiled PLCs in the Writing and Executing a PLC
Program section of this manual for more details.
variables” and integer constants that can fit in a signed 24-bit range (+/-8M), the intermediate format is
signed 24-bit integer. Refer to the section on compiled PLCs in the Writing and Executing a PLC
Program section of this manual for more details.
The general floating-point format is 48 bits long, with a 36-bit mantissa and a 12-bit exponent. This
provides a range of +2
provides a range of +2
+2047
, or +3.233 x 10
+616
, which should provide sufficient range for any foreseeable
uses of the card.