Touchprobe

Description

The TouchProbe (TP) functions are measuring functions. They detect positions relative to a rising or falling edge at a field measure input.

Once a TP function has been activated, it runs independently in the system, independent of the program. The program can use parameters to detect the state of the measuring function.

NOTE: This function is more precise if the velocity of a drive remains constant within the evaluation cycle. In cycles with high acceleration or deceleration, the precision is lower.

For more information on the accuracy of the measured positions, see the description of the CaptureValue parameter of the digital measured inputs.

NOTE: Due to the dead time of the detection of the TP event to the position evaluation, an interaction can occur if a Setpos is performed during this time. In this case, the TP position calculation is off by the Setpos manipulation. To avoid this situation, the TP limits (LowLimit and HighLimit) have to be selected appropriately so that the desired TPs are detected. As an exception, the TP position (CaptureValue) must be corrected by an amount equal to the Setpos manipulation.

Minimum Length of a Measuring Impulse

A measuring impulse must last at least twice as long as the filter time of the measuring inputs. The filter time of the inputs is 100 µs, making a measuring impulse at least 200 µs long.

Interval Between Two Measuring Impulses

The following table lists the minimum intervals between two measuring impulses that can be detected:

Device

Sercos cycles (parameter CycleTime)

PacDrive 3 LMC Pro

2

PacDrive 3 LMC Pro2

2

PacDrive 3 LMC Eco

2

PACNET BT-4/DIO1

2

Lexium LXM62 Drive with On Board I/O

  • 2.25

  • Maximum of 3 for an elementary Sercos error (8169 or 8505).

  • 3 at signal edge and first-time call of FC_TPEdge(). (Maximum of 6 for an elementary Sercos error.)

If the function FC_TPOff() is called between the calls of FC_TPEdge(), then no signal edge is created even at the first call.

Lexium LXM52 Drive with On Board I/O

Lexium ILM62 Drive Module with On Board I/O

Time of Activation

Immediately following activation of a Touchprobe by the function FC_TPEdge() in the program, the measuring function is active and waits for a valid Touchprobe event.