VDIN behaviour

andyr 2 years ago in IQANdesign updated by Gustav Widén (System support) 2 years ago 2

anyone seen this?

I have a weird situation on an MD4 whereby a VDIN button programmed as a momentary button is latching on?

The visibility and enable for the button are both controlled from an IDC channel in turn enabled when a VIN input measuring a position with a tight +/- tolerance added is in tolerance. If the input goes outside the tolerance the VDIN should go invisible and be disabled. There is the possibility the user positions the associated drive to a position just inside the tolerance band and then with a little noise/flicker on the input signal it is possible for the VDIN to effectively be switched on and off rapidly- if it gets into this situation, it seems to latch on- the button itself seems to be off (no yellow background as seen when pushed normally) but in iqan design it is definitely on. Pressing the button makes no difference either way- it remains 'on' The only way to reset it is via a hard reset (power recycle). This is obviously unacceptable and potentially not good.

i have no idea if this is firmware related or what but am interested if others have seen similar and what can be the cause


Under review

Edited the title to make it more clear this topic is about VDIN. 

I am not sure I understood everything in the description, but it almost sounds as if the button and the VDIN are somehow out of sync? 

Since you say you could see the button enabled and visible, but without the yellow indicator when the VDIN was on.

Note that I make a distinction between the button and the VDIN

In most applications, people use exactly one button for each VDIN, but there could be more. 

The properties Enable and Visible on the display page control (the button) have no effect on the channel (VDIN). 

Therefore, disabling a button does not disable the VDIN it is connected to. 

So if you need a way to make sure the VDIN is off, a suggestion is to look at using reset on the channel. 

Still, I am not sure how you could have a value on the VDIN channel that is not reflected on an enabled and visible button. 


Sorry, my previous comment where I stated that disabling the button does not clear the VDIN was wrong.

When the VDIN is not toggling, disabling disabling the button that has the keypress should clear the input. However, in versions before 6.01, it did not do this. 

From IQANdesign 6.01, disabling the button will clear the momentary input from that specific button. 


49057MD4: Touch button linked to VDIN sticks when setting Enabled to False

In this application where the button is being both disabled and made invisible, an easy solution for versions <6.01 is to skip the disable of the button. If it is just made invisible, it will no longer have the manual input.