TwinCAT NC & Drive limit error reaction issue

- 4月 09, 2020

TwinCAT NC & Drive limit error reaction issue

By advan @20200408
[Description]
Some customer use drive limit input to protect machine , This combination usually will cause NC axis error(eg 0x4650)
or lose ready flag while hit the limit sensor , In this case master is no longer to control the motor anymore
or drive the motor away limit sensor.

Or some customer use the limit sensor for calibration purpose , For this issues, This document is reference material

to avoid the error situation & achive the functionality.

In case on CoE drive , usually this issue usually been find on TC3 not TC2 .

Because “looks” TC2 did not check 0x6041 option bit 11 Internal limit active. So in TC2 & CoE drive user ,

most people don’t have this issue before . But problem occur only by change from TC2 to TC3.

In case on SoE drive(AX5000) ,Both TC2 & TC3 will check S-0-0135 bit 3 , So if TwinCAT NC controlling

AX5000 hit drive limit sensor , Both TC2 & TC3 will yield an error.

How to avoid the NC axis error?

TwinCAT NC & Tc_MC2 library provite MC_SetAcceptBlockedDriveSignal can temporarily ignore the abnormal Stateword change to avoid NC error.

https://infosys.beckhoff.com/content/1033/tcplclib_tc2_mc2/9007201474834955.html?id=8780871053429658676
See also bit 8 of the ControlDWord in AXIS_REF.

A SERCOS/SoE drive reports "Drive follows the command values" via status bit 3 of drive status word S-0-0135.

A CANopen/CoE drive reports "Drive follows the command values" via status bit 12 of object 6041h.

How to get limit sensor state

[CoE Drive] via OD 0x60FD bit 0 & bit 1

[SoE Drive](AX5000) P-0-0801
This 16 bit register map drive Input0 ~7

[Note]
Before use drive limit input, make sure NC & drive have same direction cognition , and don’t use Invert direction on controller side

To change motor direction define, Please change the direction define on drive side
i. See each drive manual. Define by each manufacturer.
ii. CoE drive OD 0x607E(Polarity) = Set 0 as default define, 224 as invent the motor direction.
Data description:
The binary representation of the object value and its corresponding meaning is as follows:

Bit number:	7	6	5	4	3	2	1	0
	Pos Polarity	Vel Polarity	Reserved

iii. SoE drive IDN S-0-0055(Position polarity parameters)

Whan using MC_SetAcceptBlockedDriveSignal function , Master must get limit sensor state(See page2 2. How to get limit sensor state) do further implement to avoid further error.

[Appendix]
CoE Drive define