Multiple Inputs-Question

[PeterW]

Is the selector switch an override of the HMI or a parallel control.

Whichever, just a 2 position selector itself would not do.

If its an override, then he would want a 3 position selector switch with two inputs.

1 - MANUAL - INPUT (Force Manual)
0 - HMI
2 - AUTO - INPUT (Force Auto)

If its to mimic the original HMI, so he can turn on/off at either, then he does not want a selector switch at all, just two pushbuttons.

 

[Lancie1]

Peter,
So far it is a maintained-contact pushbutton that overrides the HMI. However, your 3-position selector switch on the Stand looks like what I have seen before in this situation. It is a simple fix that allows Manual or Auto from the "Stand", or allows control to be switched to HMI where Man or Auto can then be selected. I think HMI should be the center position, then if "Make before break" contacts are used on Left and Right switch positions then the Stand 3-position selector can assume control and be switched to Man or Auto without dropping the machine out of Man or Auto (if the HMI has selected one or the other).

 

[OkiePC]

Thanks for all your replies. It took me while to get back to you guys. Sorry. Anyway lancie is correct. I am using a DL-06 PLC with a OP-640 panel. PLC internal "C" memory bits are mapped directly to the operator panel pushbuttons. i.e C1 and C2. These PB's does not control the stand actually. Y1 and Y2 are for status lights. There is a an exisiting AUTO/Manual PB(Maintained) on the stand. This is what actually put the stand in AUTO/Manual mode. So when I press this PB or the PB's on the OP-640 panel, I want the staus light to be turned ON. Yea and if the real PB on the stand in not in AUTO, pressing PB on the OP-640 should not be doing anything. Hope this helps.

Thanks

I don't understand why he can't have what he wants, but I agree it is a bad idea to put the system in auto from a momentary HMI PB when a maintained PB in the field is still in manual.

Unless there are safety issues, like machine setup which require the stand to "lock out" HMI control, I would swap the maintained PB for a lighted momentary one and then allow mode switching from either location, and accomodate proper indication of mode in both places. Call them both AUTO, make the lens and the HMI indicator the same color, and light them both when in AUTO.

If the maintained stand PB (or was it a selector switch) is required, just keep the same switch on the stand as the primary control, if it is in manual, then the HMI controls are active. I might even go so far as to make them conditionally visible (only visible when functional) or otherwise inform the HMI user when the STAND switch is in auto (remind them they have to go flip the stand switch first...)

Paul