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Blackmagic Design GPI & Tally interface

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Richard Carroll
Blackmagic Design GPI & Tally interface
on Feb 4, 2012 at 9:27:24 pm

I want to use one of these with a BMD video hub router to switch cross points at one panel/destination - but I cannot find out how this works.

I can't find a clear 25pin pinout or simple instructions on how to make this do what i want.

Any help gratefully received

Many thanks
Richard


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Richard Crowley
Re: Blackmagic Design GPI & Tally interface
on Feb 5, 2012 at 1:29:20 am

Define "use...with"?

The GPI/Tally gadget "outputs" simple contact closures. My understanding is that they are hard-mapped to the bus input-select buttons. It doesn't seem possible that you could use that interface to control any of the Videohub routers.

OTOH, both the production switcher products and the router products appear to be controllable via LAN. So you could use a computer to monitor the status of the production switcher and send commands of your choice to the routers also via LAN.

If the actual LAN protocol were documented, you could do it with something as small as microcontroller board (like Arduino, etc.). But it appears that BMD only documents these interfaces at the API level, so it will require a Mac or PC or Linux box and some programming skills.


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Richard Carroll
Re: Blackmagic Design GPI & Tally interface
on Feb 5, 2012 at 10:25:48 am

Thanks for your response.

I want to use this for camera touchdown/preview, using a Sony RCP 750 which offers contact closure GPI.

I'm hoping I can take the GPI out of the RCP, input it to the BMD Tally GPI box and control crosspoint routing on a BMD video hub.

I cannot find any instructions to make it do this. I'm guessing it's GPI in via the 25pin and the ethernet is connected to the video hub, either from a panel or from the ethernet router. I am also guessing the TallyGPI is programable for which cross points can be switched, or is it just 1 - 8?

Thanks
Richard


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Richard Crowley
Re: Blackmagic Design GPI & Tally interface
on Feb 6, 2012 at 12:10:27 am

Yes, I think you could do what you are attempting, but the GPI/Tally interface does NOT appear to be a viable solution.

1) The GPI/Tally interface is NOT shown as part of the Videohub family of of products. It might be compatible, but I would be very surprised. And if it WERE compatible....

2) The GPI/Tally interface does NOT seem to have the kind of INputs (or the necessary quantity) that you need for your application. Of course, the documentation for the GPI/Tally interface is essentially nonexistent, so we are only going on educated assumptions.

Again, it seems very likely that what you are asking could be done with a computer monitoring the triggers (contact closures from the CCUs) and using the API software available from BMD to send the desired switching commands to the matrix switch.


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Jim Brown
Re: Blackmagic Design GPI & Tally interface
on Feb 5, 2012 at 2:09:35 pm

I got one of these boxes and could not find any documentation as to the pinouts. So....I cut and old 25pin printer cable and metered cam 1-8 selections until I had the wires identified. Still do not know the pinouts. It does give a contact closure. I then make an interface bos that supplied power to external leds located on remote cameras.

The instructions also show GPI triggers on the remaining pins, but I did not go through the exercise to identify since I was looking purely for tally light.

Could have been a whole lot easier with some simple documentation!

Jim Brown
M&M ProductionsUSA


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Richard Crowley
Re: Blackmagic Design GPI & Tally interface
on Feb 6, 2012 at 12:20:07 am

The product photos on the website http://www.blackmagic-design.com/products/atem/models/ show that the pinout diagram is screened on the back of the box. Of course, the photo on the website is too small/fuzzy to actually see what it says. And the verbal documentation in the manuals is practically nonexistent.

Lack of documentation seems to be a chronic issue discussed in this forum. Apparently for all BMD products, not just these. It is really a shame. The products seem quite innovative and groundbreaking, but they are way too complex to provide documentation no more technically detailed than what you would get with a toaster-oven.


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Jim Brown
Re: Blackmagic Design GPI & Tally interface
on Feb 6, 2012 at 5:03:29 am

Here is pinout info from the unit.
Pins 1,2,11,12,13,14,15,24 and 25 are ground.
GPI In 1 - 8 are pins 10 to 3 (yes, they are not in ascending order!
GPI outs 1-8 are pins 23-16 ie GPI1 is pin 23

Inputs: Optical isolators triggered by connection to ground. Max 5v at 14ma
Outputs: Mechanical relay contact closure to ground Max 30v at 1amp

Connector is a DB25 connector just like the old printer connector. I found an old one here and cut the other end off and made a fan out cable. I just had to meter the cable to get to the right pens.

This information is on the back of the unit, but I had to use a magnifying glass to read it. Typical BMD.

Hope this helps anyone considering the unit.

Jim Brown
M&M ProductionsUSA


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Richard Crowley
Re: Blackmagic Design GPI & Tally interface
on Feb 6, 2012 at 6:38:37 am

Are the GPI inputs programmable? I didn't see them documented.
Are they pulled-up (contact closure)? Or do they require voltage input?


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Jeff Hartman
Re: Blackmagic Design GPI & Tally interface
on Feb 6, 2012 at 5:28:48 pm

Based on behavior with the ATEM Television Studio, input and output programming seem to be local to your switcher, rather than stored within the interface -- so whether they can be mapped would be specific to your router. (The interface seems to only know the IP address of the target switcher.) This is inferred, and my observation might not apply to the routers.

The GPI inputs are optocouplers, which typically have their anodes pulled high through a resistor, so they will stay inactive until something (a switch or equivalent) pulls the line to ground. You don't need to worry about pullup resistors, as the circuit is activated by current draw rather than voltage, and essentially forms its own pullup.

I happen to have one of these on my desk right in front of me: it takes 4.5 milliamps of current to pull a GPI line to ground, and the open circuit voltage is 2.7 volts DC. I can pull the voltage up to 12 volts with virtually no current (which is exactly what I would expect for this sort of input).

You should have no problem driving one of these inputs with most standard logic families: it's well within the limits of standard TTL and LSTTL outputs (which will tend to draw the line up around +5 volts), and just within the ability of most 74HC series outputs, which will pull the line up to whatever the chip's logic supply happens to be -- generally 5-12 volts). Driving it from a switch or relay is no problem at all.

-- Jeff


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Richard Carroll
Re: Blackmagic Design GPI & Tally interface
on Feb 14, 2012 at 10:35:26 pm

Ah well it turns out you're all wrong. Dammit!

I spoke to several BMD reps at a trade show in London today and they all said the GPI/Tally does not (currently) accept GPI in.

They said it WILL. But could not say when...

Thanks for your input.

Anyone seen my drawing board?


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Richard Burford
Re: Blackmagic Design GPI & Tally interface
on May 4, 2012 at 8:36:42 am

Just in case anyone needs a working interface try here...

http://bmrouter.co.uk


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Brian Gray
Re: Blackmagic Design GPI & Tally interface
on Sep 2, 2013 at 4:03:42 pm

August 2013 Blackmagic Matrix Touchdown capability

Just to update on this old but important thread - we are running the BMD Broadcast Video Hub with software version 5.0.2 and the BMD GPI tally interface.
Programming the GPI tally interface using the Video Hub configuration tool is straightforward and works a treat.

Individual GPIs presented to the box can create momentary or latching cross point changes ( selected in software ) to a selected destination.

Our Sony CCUs give true relay output GPIs, connected straight into the BMD GPI interface and momentarily changing the destination to the selected source - All working fine

Brian
31 Aug 13


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