Description:

This command is available starting at version 1.09 of the drum software module. The purpose of this command is to calculate and put into effect a correction offset that will compensate for dead-band drift within the drive amp (in certain specific cases).

This command applies a torque ramp to the drum and measures the point at which movement occurs. If that value of torque is above the drum friction (dfrict) then it sets the deadband offset (doff) to the measured value minus dfrict.

The nvs needs to be saved to make the value permanent. The torque numbers displayed & dfrict & doff are all in half-microseconds (which is proportional to torque.)

On drum module 1.11 and older, if the current value of doff is greater that zero then doff is not updated by drum cal. Manually set doff to zero if required.

Encoder Required: For this command to function a working encoder is required including the index pulse.

The torque numbers displayed & dfrict & doff are all in half-microseconds (which is proportional to torque.)

See procedure to set dfrict, under nvs dfrict on the nvs page.

Applies To:

• All

Syntax:

Notes:

This command is available only in drum module versions 1.09 and greater.

Before actual drum calibration is attempted, the DRUM CAL command tries to get the drum to "settle". This is done by releasing the dynamic break and setting the drum drive zero. Depending on the condition of the drum amplifier, one of the following three things can occur:

1. The drum will turn slightly then stop (i.e. reach equilibrium)
2. The drum will continue to turn slowly for an indefinite time
3. The drum will accelerate

Case 1 is usual. The calibration attempt will proceed normally after this. Case 2 and 3 are error conditions. In these cases the dynamic break will be applied and the calibration will fail because the drum wont settle. This may be as result of negative deadband in the drum amplifier. Case 2 occurs if the drum does not stop within about 15 seconds. Case 3 occurs if the speed of the drum becomes greater than 30 RPM.

See Also:

• Command: drum
• NVS: drum doff
• NVS: drum dfrict