Hand/Off/Auto logic RSLogix?

[TimD]

Hi, I am having an issue. I have an HMI touch panel hooked up to my Micrologix 1500 cpu. I have a hand/off/auto HMI button matrix on the screen.

I mapped Hand and Auto to two separate B registers in the cpu, I'll call them B3:0/0 and B3:0/1

I have two rungs:
1. one expecting normally open B3:0/0 [HAND], on close (pushed), energize plc realy output 0
2. one expecting normally open B3:0/1 [AUTO], on close (pushed), energize plc relay output 0

My problem is, only one (first rung, or HAND) button energizes the out. The HMI array automatically unlatches the out when the user presses OFF, AUTO never works.

Please help! Thanks!!!

 

[rsdoran]

Did you Branch B3:0/1 under B3:0/0 or did you make 2 rungs with the same output? If 2 rungs then the HAND is probably controlling the output.

 

[SNK]

How are your buttons configured in the HMI?
Some are NO, NC or Maintained.
You need to be clearer on the HMI settings.

 

[TimD]

Hi, the HMI buttons are latching (maintained closed on press). There are three. One is OFF (latching RESET (both 0/0 and 0/1 are set to open)), HAND (latches B3:0/0 closed), AUTO (latches B3:0/1 closed)

Either HAND or AUTO automatically unlatches the other command, if it was previously present ie. if hand to auto, auto is latched, hand us unlatched.

I have two rungs, not an OR rung, which I tried and failed.

Sorry all, I'm used to autiomation direct, and it's slightly different in RSLogix, just need to get over the curve.

Thanks!

 

[Norml]

Hi, I am having an issue. I have an HMI touch panel hooked up to my Micrologix 1500 cpu. I have a hand/off/auto HMI button matrix on the screen.

I mapped Hand and Auto to two separate B registers in the cpu, I'll call them B3:0/0 and B3:0/1

I have two rungs:
1. one expecting normally open B3:0/0 [HAND], on close (pushed), energize plc realy output 0
2. one expecting normally open B3:0/1 [AUTO], on close (pushed), energize plc relay output 0

My problem is, only one (first rung, or HAND) button energizes the out. The HMI array automatically unlatches the out when the user presses OFF, AUTO never works.

Please help! Thanks!!!

You are trying to control an output from 2 places so the first one always wins. Try adding an intermediate step so that your B3:0/0 and B3:0/1 bits are each turning on another bit. Then use the 2 new bits in parallel to turn on your output.

 

[Jimmie_Ohio]

Hi, the HMI buttons are latching (maintained closed on press). There are three. One is OFF (latching RESET (both 0/0 and 0/1 are set to open)), HAND (latches B3:0/0 closed), AUTO (latches B3:0/1 closed)

Either HAND or AUTO automatically unlatches the other command, if it was previously present ie. if hand to auto, auto is latched, hand us unlatched.

I have two rungs, not an OR rung, which I tried and failed.

Sorry all, I'm used to autiomation direct, and it's slightly different in RSLogix, just need to get over the curve.

Thanks!

A simpler way is to do the latching in the PLC, if necessary and keep the HMI buttons momentary. This way, if there is a problem, you are only looking at the PLC since it is assumed that no signal from the HMI can be "high" unless a button is being pushed.

 

[TimD]

I like the branch idea, is it the same as an OR branch?

--[B3:0/0]----------(O:0)

 |            |

 |--[B3:0/1]--|

Is this right (both inputs are XIC)

 

[bernie_carlton]

Tim - Iff you can please post:

1. Your 'or' rung which didn't work

2. Your two current rungs, which don't work either.

If you can do a screen capture then great. Otherwise in RSLogix double-click on the rung number. This will bring up the mnemonic representation of each rung. Cut and paste those into your reply.

 

[Norml]

I like the branch idea, is it the same as an OR branch?

 

--[B3:0/0]----------(O:0)

| |

|--[B3:0/1]--|

 

Is this right (both inputs are XIC)

Check to be sure that your output O:0/0 (or any output) occurs only once in the ladder. Otherwise strange and unexplainable things can happen.

 

[TConnolly]

I usually do something like this with momentary push buttons on the HMI. Often there are other permissives involved to determine whehter it is valid to select hand or auto mode as well.

 

[cntrlfrk]

Why would you use 2 separate bits for Hand and Auto? I would just have one button toggle a bit (Hand/Auto) and another button toggle a bit(On/Off) and make the On/Off button only visible when the Hand/Auto button is in Hand.

 

[TConnolly]

Either way its still two bits. Visibility animation, if wanted, is possible either way and there are times when it would not be appropriate. I can imagine scenarios where you may want to go directly from Auto to Hand/Off or Auto to Hand/On in only one step. I can also envision scenarios where an operator may not swtich from Auto without switching to Off first. It actually depends a great deal on what you are controlling.

 

[rsdoran]

Why would you use 2 separate bits for Hand and Auto? I would just have one button toggle a bit (Hand/Auto) and another button toggle a bit(On/Off) and make the On/Off button only visible when the Hand/Auto button is in Hand.

Any reply I made at this point would be just as wrong as that concept.

 

[cntrlfrk]

Any reply I made at this point would be just as wrong as that concept.

???

 

[Tharon]

He's saying that the idea was a bad one.

But really, if you are using an HMI pushbutton for a Hand/Off/Auto switch, it's not like you are losing or gaining anything by having an on/off selection and a hand/auto selection seperate, since the switch isn't hard wired anyway.