236 ● TM DMC-40x0 Command Reference
TM
FUNCTION: Update Time
DESCRIPTION:
The TM command sets the sampling period of the control loop. A zero or negative number turns
off the servo loop. The units of this command are μsec.
ARGUMENTS: TM n where
With the fast firmware: n is an number in the range 31.25 to 20000 decimal with resolution of
31.25 microseconds. The minimum sample time is possible when using the fast firmware. In
the Fast firmware mode the following functions are disabled: TD, DV, TK, NB, NZ, NF,
second field of EI, Gearing, CAM, PL, Analog Feedback, Steppers, Trippoints in all but
threads 0 and 1, Data Record and TV. Using the fast firmware the minimum sample times are
the following:
Accelera Controllers with 1-2 axes
31.25 μsec
Accelera Controllers with 3-4 axes
62.5 μsec
Accelera Controllers with 5-6 axes
93.75 μsec
Accelera Controllers with 7-8 axes
125 μsec
With the normal firmware: Using the normal firmware the minimum sample times are the
following:
Accelera Controllers with 1-2 axes
62.5 μsec
Accelera Controllers with 3-4 axes
125 μsec
Accelera Controllers with 5-6 axes
156.25 μsec
Accelera Controllers with 7-8 axes
187.5 μsec
n = ? returns the value of the sample time.
USAGE: DEFAULTS:
While Moving Yes Default Value 1000
In a Program Yes Default Format 1.0
Command Line Yes
Controller Usage
ALL CONTROLLERS
OPERAND USAGE:
_TM contains the value of the sample time.
EXAMPLES:
TM -1000 Turn off internal clock
TM 2000 Set sample rate to 2000 usec
TM 1000 Return to default sample rate
NOTE: TM1000 actually specifies a servo update rate of 976
μ
s