Hi. Just as the subject says, can the K8055/VM110 Digital Outs activate relays? If so, what would be the specs of the relays? 5vdc?
Would like to use the D/O’s to activate a relay that will toggle a audio console channel OFF via the console logic connections.
Thanks,
Scott
You should read the assembly manual for the K8055.
There are examples in it for connecting relays.
You can download it here.
http://www.vellemanusa.com/downloads/0/illustrated/illustrated_assembly_manual_k8055_uk_rev3.pdf
[quote=“Wrong Way”]You should read the assembly manual for the K8055.
There are examples in it for connecting relays.
You can download it here.
http://www.vellemanusa.com/downloads/0/illustrated/illustrated_assembly_manual_k8055_uk_rev3.pdf[/quote]
LOL… I did. Didn’t see one example or specs on what type relay can be used on the 8 digital outs.
Thanks.
Look on page 19 right side of the board
They have a relay and an LED.
You can use up to 50volts 100mA
Specifications
5 digital inputs (0= ground, 1= open) (on board test buttons provided)
2 analog inputs with attenuation and amplification option (internal test +5V provided)
[color=#BF0000] 8 digital open collector output switches (max. 50V/100mA)[/color] (on board LED indication)
2 analog outputs:
0 to 5V, output resistance 1K5
PWM 0 to 100% open collector outputs max 100mA / 40V (on board LED indication)
general conversion time: 20ms per command
power supply through USB: approx. 70mA
dimensions: 5.7 x 3 x 0.8"
Thank you. I did see that in the manual. Just looking for confirmation on that. Thanks again.
No problem.
Enjoy your kit.
I noticed the digital outs actually create a dry contact closure, which is exactly what I needed for what I want to do. So no need for a relay on the outs. 
That depends on what you actually intend to control with it and how many of that simultaneously.
The digital outputs are so called “open collector” outputs. They act like a transistor with the collector being the output port and the emitter connected to ground.The K8055’s micro controller is connected to the base. When the micro controller’s output is going high, the corresponding digital output port has a small resistance from collector to emitter. Otherwise the resistance is high.
The ULN2803 on the board can actually switch up to 500mA per output port. But not all at the same time. There is a forward voltage drop and that multiplied by the current switched is the heat (in Watts) that the IC needs to dissipate. At 25 degrees Celsius ambient temperature, the IC can dissipate 1.47W. With a 2V drop, two ports at 500mA load would already exceed that. But 8 ports all turned on at 50mA load would not.
So it depends on the load you want to control if you need a relay, maybe just a power transistor or nothing.
Regards,
Jan
That depends on what you actually intend to control with it and how many of that simultaneously.
The digital outputs are so called “open collector” outputs. They act like a transistor with the collector being the output port and the emitter connected to ground.The K8055’s micro controller is connected to the base. When the micro controller’s output is going high, the corresponding digital output port has a small resistance from collector to emitter. Otherwise the resistance is high.
The ULN2803 on the board can actually switch up to 500mA per output port. But not all at the same time. There is a forward voltage drop and that multiplied by the current switched is the heat (in Watts) that the IC needs to dissipate. At 25 degrees Celsius ambient temperature, the IC can dissipate 1.47W. With a 2V drop, two ports at 500mA load would already exceed that. But 8 ports all turned on at 50mA load would not.
So it depends on the load you want to control if you need a relay, maybe just a power transistor or nothing.
Regards,
Jan[/quote]
Jan,
Thanks for the information. I’m going to be using the card as a GPIO for broadcast automation software to interface with a broadcast console. All I need the DO’s to do is make a momentary dry contact closure. This, in turn, will signal a audio channel on a broadcast console to turn OFF. Once it’s OFF the channel stays OFF until the operator turns it ON again. I might also have the card flash the LED for a few seconds afterwards as this can also be connected to a “ready” light on the console which flashes the OFF button.
As long as the connection you are making is DC and does not exceed 50V or 100mA in load, that should work. Remember that if you are switching an inductive load (relay coil, motor or the like), you need to connect the +V of that circuit to CLAMP of the K8055 so that the protective Zener diodes in the ULN2803 can do their job.
For the flashing light I suggest using another digital out channel with the proper support circuit depending on what light source actually is in that ready light or off button (bulb or LED). The LEDs on the K8055 together with the inputs of the ULN2803 are powered directly by the micro controller’s ports. Unless you know exactly what you are doing and compare the resulting total mA against the PIC’s datasheet, you should not connect anything in parallel to that LED. The PIC ports can only provide a few milliamps and overloading them could damage the PIC, which is rather difficult to replace since Velleman does not publish the source or hex files for the firmware. The ULN2803 is much easier to get and is much cheaper too.
Regards,
Jan
[quote=“MostlyHarmless”]As long as the connection you are making is DC and does not exceed 50V or 100mA in load, that should work. Remember that if you are switching an inductive load (relay coil, motor or the like), you need to connect the +V of that circuit to CLAMP of the K8055 so that the protective Zener diodes in the ULN2803 can do their job.
For the flashing light I suggest using another digital out channel with the proper support circuit depending on what light source actually is in that ready light or off button (bulb or LED). The LEDs on the K8055 together with the inputs of the ULN2803 are powered directly by the micro controller’s ports. Unless you know exactly what you are doing and compare the resulting total mA against the PIC’s datasheet, you should not connect anything in parallel to that LED. The PIC ports can only provide a few milliamps and overloading them could damage the PIC, which is rather difficult to replace since Velleman does not publish the source or hex files for the firmware. The ULN2803 is much easier to get and is much cheaper too.
Regards,
Jan[/quote]
Jan,
Again thanks for the info. I appreciate it very much.
The audio console is DC powered (the external power supply converts AC to DC) and breaks out to a negative (I think) 48vdc for a condenser mic (if so desired), a 13vdc for Lights and Logic, and a 16vdc for audio in the que speaker, control and studios and headphones. The console logic isn’t anywhere close to the current you mentioned. The K8055 will simply make a dry contact closure for no more than 500 ms on the respective DO, this will connect to the console logic for the “OFF” tally signal for the respective channel. Then the respective DO on the K8055 will return back to open, otherwise the audio channel won’t be able to be switched back ON by the air talent when needed because the K8055, via the console logic, would keep it in an OFF state.
Regarding the lights in the console buttons, my plan was to use DO 1-4 to signal the channels off (since I have 4 playback channels for the automation software), then use DO 5-8 to do the “ready” light blinking. The console buttons use either a 12vdc bulb or a 12vdc LED (I use LED’s). The light itself draws power from the console power and wouldn’t be drawing power from the K8055. All the DO’s on the K8055 would do in this implementation is connect to the specific pin on each channel logic point and would alternate between open and close to produce the blinking affect, for say 10 seconds, then remain closed to signal console logic to keep the OFF button illuminated - we call this a “ready” light in the broadcast business.
Basically, I’m using the K8055 as a GPIO card to interface with the broadcast automation software and the console.
That should work. As you figured, the K8055 can act as a 100mA switching dry contact. In electronics the type of circuit presented by the digital outputs of the K8055 is called “open collector” and is usually placed between the load and ground.
Thank you for taking the time to explain this. I always like to learn things about other fields.
Let me see if I understood the whole plan. In order to do that I’m going to try to write a mini-functional-specification for one single channel in list form. I’m a software engineer by day and this is the easiest way for me to get a complete picture.
[ul][li]The audio console has an input that when connected to GND turns the channel off. One DO of the K8055 will connect that input to GND for 500ms to trigger the OFF action.[/li]
[li]The audio console has an input that when connected to GND turns the “ready light” on. A second DO of the K8055 will connect that input to GND to turn the light ON.[/li]
[li]Using these two DOs the software controlling the K8055 will trigger the OFF action and at the same time start a blinking action on the “ready light”.[/li]
[li]After some time (10 sec) of blinking, the software will leave the light ON.[/li][/ul]
So far so good or correct me if I misunderstood. What I am missing here is how the K8055 controlling software knows when to turn that “ready light” back off. My intuition tells me that that should happen when the operator pushes that button, which turns the audio channel ON again. This would require some sort of signal from the audio console to the K8055 when that button is pushed. Is there anything that could be used with the digital inputs? Either an output signaling that the button is currently pressed, or maybe something that indicates that the channel is currently active.
Regards,
Jan
[quote=“MostlyHarmless”]That should work. As you figured, the K8055 can act as a 100mA switching dry contact. In electronics the type of circuit presented by the digital outputs of the K8055 is called “open collector” and is usually placed between the load and ground.
Thank you for taking the time to explain this. I always like to learn things about other fields.
Let me see if I understood the whole plan. In order to do that I’m going to try to write a mini-functional-specification for one single channel in list form. I’m a software engineer by day and this is the easiest way for me to get a complete picture.
[ul][li]The audio console has an input that when connected to GND turns the channel off. One DO of the K8055 will connect that input to GND for 500ms to trigger the OFF action.[/li]
[li]The audio console has an input that when connected to GND turns the “ready light” on. A second DO of the K8055 will connect that input to GND to turn the light ON.[/li]
[li]Using these two DOs the software controlling the K8055 will trigger the OFF action and at the same time start a blinking action on the “ready light”.[/li]
[li]After some time (10 sec) of blinking, the software will leave the light ON.[/li][/ul]
So far so good or correct me if I misunderstood. What I am missing here is how the K8055 controlling software knows when to turn that “ready light” back off. My intuition tells me that that should happen when the operator pushes that button, which turns the audio channel ON again. This would require some sort of signal from the audio console to the K8055 when that button is pushed. Is there anything that could be used with the digital inputs? Either an output signaling that the button is currently pressed, or maybe something that indicates that the channel is currently active.
Regards,
Jan[/quote]
Jan, you are spot on and NO you aren’t missing anything in the implementation. I just didn’t dive that far into it with the above post. Since you asked… the console itself doesn’t make a simple “dry” contact closure. Simple 12vdc relays connected to the appropriate point of the channel logic circuit are used to achieve a contact closure. That said, when the DJ presses the ON button, it causes the relay to make a contact closure (the console logic can send a momentary pulse or a constant closure to the relay while the ON button is active). The relays for the four playback channels will connect to DI 1, 2, 3 & 4 of the K8055. Since the DO 1 - 4 closures will be momentary for turning the channels OFF via the K8055, and the flashing of the off button will be on DO 5- 8, then when any of the four DI’s go active from pressing the ON button everything should work LOL. I hope.
On a related note, thanks for letting me know you’re a software engineer… I have just engaged a friend who also does software to help me develop some broadcast automation software. We may need to call on your expertise for integrating the K8055 code into the program, if that is ok with you. Right now, all I am doing is testing my theory with the manual input buttons and the K8055 demo app to turn the channels off and blink the lights…
If you’re curious about what I’m doing, “google” broadcast automation software. This will give you insight into this particular software marketplace. Several different variations to do the same thing, which is play music to listeners LOL. You can also search for PR&E Radiomixer console to see the console I’m working with.
Again, thanks for your feedback on this topic. Much appreciated.
Scott