ElmoMC SimplIQ Command Reference - Manual (Page 157)

TS - Sampling Time
Purpose:
To define the sampling time of the drive, in microseconds. TS is the sampling time of the
current loop. The sampling time of the velocity controller is two times TS and the
sampling time of the position controllers (UM=4, 5) is four times TS. For example, if
TS=80, the torque/commutation controller runs once every 80 microseconds, the speed
controller executes every 160 microseconds, and the position controller executes every
320 microseconds.
The selection of TS is a compromise between high servo performance and the scan loop
(background) operations, such as user program and interpreter responses. A low TS
enables the drive to achieve more control bandwidth, but at the same time, it increases
the computational burden on the CPU, so that less computing power remains for
executing interpreter and user program commands.
The drive does not allow an excessively low value for TS to prevent an overflow of the
required CPU computing power.
For all unit modes, WS[28] gives the actual sampling time of the speed controller and
WS[55] gives the actual sampling time of the position controller.
Notes:
ƒ When TS is modified, the current loop gains must be retuned in order to prevent
instability of the current loop, which may damage the drive and/or the motor.
ƒ Too short a TS value will cause a CPU stack overflow. If a stack overflow occurs,
change TS in order to start the motor and reset the CPU stack overflow errors.
Setting a new value for TS removes all stack overflow history. This should be
avoided.
ƒ Speed limit values (VH[2],VL[2],HL[2],LL[2]) depend on TS value (refer to the LL
command for more information).
ƒ Use WI[7] to measure the CPU load. WI[7] returns the CPU percentage remaining
for interpreting user commands and running the user program. Use WI[7] in true
working conditions, because the CPU load changes with the order of the control
filter and other working conditions, like the motion mode does.
ƒ The smooth factor range (SF command) depends on the range of TS. The actual SF
can be retrieved by WI[22].
Attributes: Type: Parameter, Integer
Source: RS-232, CANopen
Restrictions: MO=0, User program not running
Default value: 90 (RS), Non-volatile
Range: [70…120]
Unit modes: All
Activation: Immediate
See also:
WI[N], WS[N]
SimplIQ Command Reference Manual Alphabetical Listing
MAN-SIMCR (Ver. 4.5)
3-144