# Is it possible to monitor inputs and outputs from a device to enable current flow on a circuit?

#### Riskinit

Joined Jan 28, 2022
59
I have this device below; an Advantech WISE-S250 device which contains 6 inputs and 2 outputs.

I also have an EATON HT8GDBF3 which serves as an input (button) and an output (internal light to button).

I want to build a circuit where the user triggers an input (button) and a corresponding output (internal light to button) is turned on in response.

Input 1 + Output 1 == Light 1 turns on.
Input 2 + Output 1 == Light 2 turns on.
Input 3 + Output 1 == Light 3 turns on.
Input 4 + Output 1 == Light 4 turns on.

The problem I have is my inputs are all momentary. Once the user releases a button the input is no longer present. Is there a way, in hardware, to remember what the user last pressed?

#### eetech00

Joined Jun 8, 2013
3,154
I have this device below; an Advantech WISE-S250 device which contains 6 inputs and 2 outputs.

I also have an EATON HT8GDBF3 which serves as an input (button) and an output (internal light to button).

I want to build a circuit where the user triggers an input (button) and a corresponding output (internal light to button) is turned on in response.

Input 1 + Output 1 == Light 1 turns on.
Input 2 + Output 1 == Light 2 turns on.
Input 3 + Output 1 == Light 3 turns on.
Input 4 + Output 1 == Light 4 turns on.

The problem I have is my inputs are all momentary. Once the user releases a button the input is no longer present. Is there a way, in hardware, to remember what the user last pressed?
You could use a D type flip flop (with debounce) for each input.
But we need to know logic levels, supply voltages and load current

#### Riskinit

Joined Jan 28, 2022
59
You could use a D type flip flop (with debounce) for each input.
But we need to know logic levels, supply voltages and load current
The WISE-S250 uses 1.2 W at 24 VDC (approximately 50 mA).
The power supply I am using produces 125 mA at 24 VDC and I can upsize as needed.
The outputs on the WISE-S250 are 100 mA (sink type).
The inputs on the WISE-S250 are dry contact and can operate on regular or inverted logic.

The Eaton pushbutton/light unit doesn't mention how much power the LED light pulls.
https://www.eaton.com/us/en-us/skuPage.HT8GDBF3.specifications.html

#### MrChips

Joined Oct 2, 2009
26,099
Welcome to AAC!
What you want is doable. We just need to work through the details.

#### Riskinit

Joined Jan 28, 2022
59
Welcome to AAC!
What you want is doable. We just need to work through the details.
Thank you!

My experience with circuits goes back to my digital design class in 2012 so forgive me if I state something incorrectly.

In the screenshot above I would have my button as the data and I would take Q and using an AND gate with my output I would generate a final output that turns on the LED light.

Is there a D-type Flip-Flop that operates at 24 VDC? What would I use for a clock signal? How do I AND to a sinking type OUTPUT?

#### Ya’akov

Joined Jan 27, 2019
5,660
Could you explain what the application of this is? It’s helpful to know the context in case there are issues not obvious in your constrained description.

#### Riskinit

Joined Jan 28, 2022
59
Could you explain what the application of this is? It’s helpful to know the context in case there are issues not obvious in your constrained description.
Sure, the end-user of this system wants to have visual feedback that their request for help has been acknowledged by a server. The end-user can press 4 physical buttons (EATON HT8GDBF3) corresponding to various end-user requests. The WISE-S250 sends these inputs to a server (over wi-fi) which will send back a signal (over wi-fi) to turn on an output.

Because the WISE-S250 has 2 outputs I can't directly hook up an output to an LED. I have to have a circuit that remembers what button the user last pressed.

The combination of the user input + the output feedback from the server is what I have to use to turn on an LED.

#### Ya’akov

Joined Jan 27, 2019
5,660
Two bits get you four outputs: 00 01 10 11, this can easily be turned into one of four lights on.
If your other output isn’t going to be used, I would just decode rather that store state externally. Since the device is directly operating the annunciations, you reduce the problems caused by an open loop system where the server can‘t know the external state.

Just a suggestion.

EDIT: I just realized you are probably going to need one more bit since all lights off is a valid state, so this is probably not correct, sadly.

#### Ya’akov

Joined Jan 27, 2019
5,660
I’m curious how you ended up with this device for this application. I am sure it is very expensive and it’s poorly suited to this particular job. Is it doing something else at the same time?

#### Riskinit

Joined Jan 28, 2022
59
I’m curious how you ended up with this device for this application. I am sure it is very expensive and it’s poorly suited to this particular job. Is it doing something else at the same time?
Surprisingly, it is cheaper to go over wi-fi instead of having a hardwired system. Imagine you are 1 mile away from the server and are requesting help. There is a lot of distance between the end-user and the server.

Could I use the output from the WISE-S250 as my clock input on the D-Flip-Flop? Aka, press the button until visual feedback is confirmed.

I have been looking for a 24 VDC D-Flip-Flop but haven't found anything yet.

#### Ya’akov

Joined Jan 27, 2019
5,660
It‘s not the WiFi I was wondering about. Is this in location that requires certifications, or ruggedized hardware, or something? It just seems really both over- and under-spec‘d if this is all it is doing.

To do what you are asking, I would expect, roughly, you want to use the switch for input to two things 1) the WISE device to call for help, two something that is responsible for latching the acknowledgement annunciator on so long as the DO from the WISE is active (by the way the specification appear to indicate the outputs are sink, not source so keep that in mind).

Once the light is on, the button can be released because it’s input is no longer needed, the DO signal will keep whichever light was illuminated on until it drops, then everything is cleared.

This is not very hard to do if you are going to build a circuit, but if you want off the shelf parts it be difficult.

What is supposed to happen if the user presses another button before the first one is cleared?

Given that you are willing to drop a lot of cash on the WISE, could you consider using a PLC?

#### Riskinit

Joined Jan 28, 2022
59
It‘s not the WiFi I was wondering about. Is this in location that requires certifications, or ruggedized hardware, or something? It just seems really both over- and under-spec‘d if this is all it is doing.

To do what you are asking, I would expect, roughly, you want to use the switch for input to two things 1) the WISE device to call for help, two something that is responsible for latching the acknowledgement annunciator on so long as the DO from the WISE is active (by the way the specification appear to indicate the outputs are sink, not source so keep that in mind).

Once the light is on, the button can be released because it’s input is no longer needed, the DO signal will keep whichever light was illuminated on until it drops, then everything is cleared.

This is not very hard to do if you are going to build a circuit, but if you want off the shelf parts it be difficult.

What is supposed to happen if the user presses another button before the first one is cleared?

Given that you are willing to drop a lot of cash on the WISE, could you consider using a PLC?
The location requires ruggedized hardware (EATON HT8GDBF3) because the end-user can't be trusted to be gentle with the equipment. The WISE-S250 was chosen because it is a proven product with technical support available and a 2 year warranty on parts. A much cheaper solution might be an Arduino or Raspberry Pi with a Wi-Fi module but we would lose out on the warranty and technical support (and built-in encryption).

A PLC was considered but then physical wires would have to be run to each station. The WISE-S250 with it's base costs $250 so it would be unlikely the wiring could be run for less money and the wi-fi modules also allow the end user to move the unit easily. I hope all that clarifies why this path is being pursued. I found this D-Flip-Flop. https://www.farnell.com/datasheets/1723951.pdf It seems to be the most promising solution so far except it doesn't quite meet the 24 VD specs. #### Ya’akov Joined Jan 27, 2019 5,660 I was suggesting you might use the PLC in conjunction with the WISE. It would allow you to handle more complicated behaviors including timeouts. The PLC would take the switch inputs and the DO signal from the WISE and manage the annunciators. You could even extend the behavior using the second DO if needed. It seems to be having some programmability is going to be helpful. I can imagine getting what seems like a simple request for a behavior change that turns out to be much more complicated because you are strictly using hardware. #### eetech00 Joined Jun 8, 2013 3,154 Sure, the end-user of this system wants to have visual feedback that their request for help has been acknowledged by a server. The end-user can press 4 physical buttons (EATON HT8GDBF3) corresponding to various end-user requests. The WISE-S250 sends these inputs to a server (over wi-fi) which will send back a signal (over wi-fi) to turn on an output. Because the WISE-S250 has 2 outputs I can't directly hook up an output to an LED. I have to have a circuit that remembers what button the user last pressed. The combination of the user input + the output feedback from the server is what I have to use to turn on an LED. Just a suggestion... If there is only one button and one light, then: Might want to consider a "fast flashing" the pushbutton LED went the request is sent. Then, when the request is acknowledged (executed) the LED lights steady on. When the button is pressed to cancel the request, "slow flash" the LED. When the request to cancel is acknowledged, the LED goes steady dark. Or something similar to this.. #### eetech00 Joined Jun 8, 2013 3,154 The WISE-S250 uses 1.2 W at 24 VDC (approximately 50 mA). The power supply I am using produces 125 mA at 24 VDC and I can upsize as needed. The outputs on the WISE-S250 are 100 mA (sink type). The inputs on the WISE-S250 are dry contact and can operate on regular or inverted logic. Do you have a document that shows a connection diagram for the WISE-S250 dry contacts? Also for the outputs? #### eetech00 Joined Jun 8, 2013 3,154 The location requires ruggedized hardware (EATON HT8GDBF3) because the end-user can't be trusted to be gentle with the equipment. The WISE-S250 was chosen because it is a proven product with technical support available and a 2 year warranty on parts. A much cheaper solution might be an Arduino or Raspberry Pi with a Wi-Fi module but we would lose out on the warranty and technical support (and built-in encryption). A PLC was considered but then physical wires would have to be run to each station. The WISE-S250 with it's base costs$250 so it would be unlikely the wiring could be run for less money and the wi-fi modules also allow the end user to move the unit easily.

I hope all that clarifies why this path is being pursued.

I found this D-Flip-Flop.

https://www.farnell.com/datasheets/1723951.pdf

It seems to be the most promising solution so far except it doesn't quite meet the 24 VD specs.
You do realize that if you use chips you will have to make a circuit board of some type right?
Have you considered toggle or alternate action lighted buttons?

What do they mean "dry contacts" for inputs?

#### Riskinit

Joined Jan 28, 2022
59
Do you have a document that shows a connection diagram for the WISE-S250 dry contacts?
Also for the outputs?
I don't have anything specifically... take a look at the attached pictures/screenshots and let me know if I can seek any more information.

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#### eetech00

Joined Jun 8, 2013
3,154
I don't have anything specifically... take a look at the attached pictures/screenshots and let me know if I can seek any more information.

View attachment 259292
I'm concerned with the I/O on the device.

I would think that the inputs would be opto couplers and the outputs would be "dry contacts".

#### Riskinit

Joined Jan 28, 2022
59
You do realize that if you use chips you will have to make a circuit board of some type right?
Have you considered toggle or alternate action lighted buttons?

What do they mean "dry contacts" for inputs?
I am comfortable building circuit boards if the parts are all reliable. I have considered another WISE advantech module that supports 4 outputs but it has a 7-8 month lead time currently.

https://electronics.stackexchange.com/questions/80841/what-is-a-dry-contact-input
"Dry contact means no energy is supplied to the contacts (completely passive and isolated). In order for the DAQ to read it, it needs to have a defined voltage"

#### eetech00

Joined Jun 8, 2013
3,154
I am comfortable building circuit boards if the parts are all reliable. I have considered another WISE advantech module that supports 4 outputs but it has a 7-8 month lead time currently.

https://electronics.stackexchange.com/questions/80841/what-is-a-dry-contact-input
"Dry contact means no energy is supplied to the contacts (completely passive and isolated). In order for the DAQ to read it, it needs to have a defined voltage"
I know what dry contact are, thanks. I'm just not confident the document is accurate.

Usually dry contacts are available as outputs, not inputs.
And optocouplers used for inputs. This is to electrically isolate the internal circuits of the device from external voltages.

We need to know this before moving forward, so we can properly interface the new circuit to the device.