Compact Video Hub RS422 Problems

[Bob Zelin]

I am going to make a simple suggestion, since I am afraid I do not understand your exact application –
you state –
“We built a device which communicates with the compact video hub through the RS422 port so that we could use the RCP’s touchdowns to control the switching aswell (using the Blackmagic protocol and the Leitch Serial Pass-Through Protocol as reference).”

These RS422 ports on the Compact Video Hub are designed for SonyP2 protocol VTR control. May I suggest that you simply hook up a couple of VTRs directly to the back of the Compact Video hub (RS422 ports using straight thru 9 pin cables) and see if you can get the VTR’s to talk to each other. This is what they are designed to do.
It’s a simple pass thru for RS422 communication (VTR control). I don’t know what RCP touchdowns are (remote control panel ? ) – exactly what are these – who makes them – are they controlling VTR’s ? Is that what they are designed to do – are you trying to route these RCP’s to VTRs ? or is there another application ?

Bob ZElin

[Stefan Fox]

Hi Bob,

The Compact Videohuub has a dedicated RS-422 port ‘for custom crosspoint control'(it doesn’t have any for VTR control).
It runs on the Leitch Serial Pass-Through Protocol (https://www.leitch.com/custserv/doclib.nsf/55f584d47a8fd27585256bf300554e9f/607933f430bc5cae85256e9300736b4f/$FILE/SPR_manual.pdf)
See section 4

So with this 422 port you can sent commands to the videohub to control the routes, get route states, ect.

The RCP’s we mainly use is the Sony RCP750 (https://www.tnpbroadcast.co.uk/sony-rcp750-remote-control-panel-p-657.html), but it doesn’t really matter as I think all touchdown controls on any RCP is just a closing contact relay.

So all our device does is when you press the touchdown, it sends a command to the video hub to see which source the particular destination is set to (and stores it in memory for later). Then it sends another command to tell it to switch to the source the RCP is controlling. When you let go of the RCP it tells the videohub to switch back to the source stored in memory.

Nothing too dificult.

Thanks,
Stefan.

[Fredric Tirheden]

Hi Stefan!

I’m interested to know if you solved the problem?

We are also building a new small OB truck and are planning to buy a BMD videohub to use it together with 4 of Sonys RCP-750.

“We built a device which communicates with the compact video hub through the RS422 port”

What kind of a device did you build to make it work?

/Fredric

[Stefan Fox]

Hi Fredric,

‘What kind of a device did you build to make it work?’

We built an interface between the touchdowns and the Video Hub based on a microcontroller.

Using these protocols:
https://www.blackmagic-design.com/media/1388225/VideohubManual.pdf
p82

Also reading the Leitch Serial Pass-Through Protocol (Section 4) will help.

‘I’m interested to know if you solved the problem?’
This is something that Blackmagic is working on, but if you don’t use the ‘Ref in’ it will work well.

Regards,
Stefan.

[Alan Drake]

Hi Stefan and Fredric

Have you managed to solve the issues of touchdowns with Blackmagic RS422?

Where did you get your Touchdown controllers. I am looking to purchase one for a 4 camera PPU I am building.

Cameras are Sony HXC100
Matrix is 40 x 40 Black magic

Cheers
Alan

[Fredric Tirheden]

Hi!

Well in english it is not easy for me to explain what we are still working on. But I will give it a try.

We bought the BMD Smart Control and connected it to our Studio hub. As there is no 422-port in the Studio hub we’ve got some help from a technician we know who soldered inside the smart control and made a D-sub connector. We then connected the smart controls D-sub to a device where we connect all the RCP’s. Because all the touchdown works as on/off buttons the guy who’s helping us also will build in the device some kind of “relay” (don’t know if this is the correct english) that works like this when you release the touchown it will go back to PGM. Without this you always have to press a button manually to make the smart control to go back to PGM.

We have also heard that BMD is building some kind of a GPI-device which will be released 2012Q1. A lot of people are asking for this. That is very interesting.

//Fredric

[Stefan Fox]

Hi Alan,

We built our own controllers based on BlackMagic’s RS422 protocol, and the only problem now is that the VideoHub will stop communicating after a while when you have the Ref in connected (Genlock).

So as a work aroung we disconnected this from the VideoHub, and it works as it should.

I see there is an update for the VideoHub, so this ‘might’ solve the problem. When I have some time I will see if it does.

Stefan.

[Richard Carroll]

Hello All,

I’m just wondering if anybody has got a simple method of making this work.

Still no sign of a GPI device from BMD.

I too am after simple over press for cameras

I’ll contact BMD direct too, any useful information I’ll post back here.

Thanks
Richard

[Stefan Fox]

Hi Richard,

Yes it is possible to make one (we use one all the time), all the info you need is in this thread.

But be aware that even with the latest updates the Videohub will crash(stop communicating over RS422), unless you have Ref In disconnected.

Regards,
Stefan.

[Richard Burford]

Just in case anyone is interested, I have made an interface.

Details here

https://bmrouter.co.uk