With some simple componenets it's posisble to use the Midi Solutions R8 to provide TALLY to (for example) the Hollyland Mars T1000

Please find a PDF with all instructions at the end of this post

The Mars T1000 Intercom system provides a TALLY options using an (optional) tally Interface (DB25 connector)
The pinnout is:

Ground = 13
tally 1: 1=PGM, 14=PVM
tally 2: 2=PGM, 15=PVM
tally 3: 3=PGM, 16=PVM
etc

The MidiSolutins R8 has 8 relay outputs (unfortunately they are using the more "audio standard" JACK connectors (mono))
So some soldering is required :)
see above the pinnout for soldering the DB25.

YOU DON'T NEED A POWER SUPPLY for the Midi Solutions R8
The power is arranged over the DIN connector (Midi OUT) using an old USB cable.
Connect the "Ground" (minus) to pin 2
Connect the "Plus" (5V) to pin 4 and 5.

Programming the MidiSolutions R8
on the web pahes of MidiSolutions you will find a link to their programming software.
http://www.midisolutions.com/progtool.htm
Don't bother reading the manual (worst manual I have ever read)

Open the programming tool.
Do NOT select relay, but R8 (at the bottom)
if you do select Relay and not R8 programming will not function :(

Make sure your script looks like the following:

F0 00 00 50 26 00 F7
{ R8 Clear All Settings }

F0 00 00 50 26 02 00 02 01 0A 40 F7
{ Program Rel1 of the R8 to CLOSE when the value of Control Change #1 on MIDI Channel 11 is above or equal to 64, and OPEN when it is below (right-click to edit) }

F0 00 00 50 26 02 01 02 02 0A 40 F7
{ Program Rel2 of the R8 to CLOSE when the value of Control Change #2 on MIDI Channel 11 is above or equal to 64, and OPEN when it is below (right-click to edit) }

F0 00 00 50 26 02 02 02 03 0A 40 F7
{ Program Rel3 of the R8 to CLOSE when the value of Control Change #3 on MIDI Channel 11 is above or equal to 64, and OPEN when it is below (right-click to edit) }

F0 00 00 50 26 02 03 02 04 0A 40 F7
{ Program Rel4 of the R8 to CLOSE when the value of Control Change #4 on MIDI Channel 11 is above or equal to 64, and OPEN when it is below (right-click to edit) }

F0 00 00 50 26 02 04 02 0B 0A 40 F7
{ Program Rel5 of the R8 to CLOSE when the value of Control Change #11 on MIDI Channel 11 is above or equal to 64, and OPEN when it is below (right-click to edit) }

F0 00 00 50 26 02 05 02 0C 0A 40 F7
{ Program Rel6 of the R8 to CLOSE when the value of Control Change #12 on MIDI Channel 11 is above or equal to 64, and OPEN when it is below (right-click to edit) }

F0 00 00 50 26 02 06 02 0D 0A 40 F7
{ Program Rel7 of the R8 to CLOSE when the value of Control Change #13 on MIDI Channel 11 is above or equal to 64, and OPEN when it is below (right-click to edit) }

F0 00 00 50 26 02 07 02 0E 0A 40 F7
{ Program Rel8 of the R8 to CLOSE when the value of Control Change #14 on MIDI Channel 11 is above or equal to 64, and OPEN when it is below (right-click to edit) }

Don't worry about the complex numbers.
Some programmer thought it was necesarry to make us User worried about hexadecimal programming.
Luckily the interface gives you the option to select what you want and leave the programming where it belongs...

With Setting select control change
select the relay
select which Midi Channel you want to use
select the midi note (don't mind what has been written, just select the note required)
and set the threshold to 64 (default)

after you have created the script (which relay closes on which midi note) you must UPLOAD it to the MidiSolutions R8
for that you will need a Simple USB-Midi device like the M-Audio UNO (or similar)

connect the "to midi in" connector (from the M-Audio Uno) to the "Midi IN" connector of the R8
(for more basic USB_Midi devices it might just say "Midi-Out" that connects to "Midi-IN" of the R8)

Select Program in the Midi Solutions Programming software and start uploading
The R8 has a RED LED at the front that quickly flashes and goes OFF for a second and keeps doing that till all the programming has been done.

Now the R8 is (finally) ready to do it's thing, But first you need to use ACTIVATORS in Vmix
As we are using only 4 intercom sets (with Green and Red indicating PVM and PGM)I have created 4 "input" activators
The type of activator the "Control Change" and VOLUME
select the correct midi Channel, the correct note and set it to 127

in my case:
In my R8 programming you can read I have used the following
Program Rel1 of the R8 to CLOSE when the value of Control Change #1 on MIDI Channel 11 is above or equal to 64, and OPEN when it is below
I want the relay to activate ones it receives a value higher then 64 on note 1 on midi channel 11.

Most Midi equipment can only handle 1 channel, like Behringer and X-Touch
in that case you have only 128 notes available for activators AND Shortcuts
By using a completely different channel (like in the abovem channel 11) you seperate the Tally from all other activators and /or shortcuts.

So my actovator reads:

Control: ControlChange
Channel 11 Note 1 to 127
Event: INPUT
Input: 1, Camera 1
Type: FADER

Repeat this 3 times for camera 1 - 4.

For the Preview
I programmed relay 5 to close on note 11 channel 11)
Program Rel5 of the R8 to CLOSE when the value of Control Change #11 on MIDI Channel 11 is above or equal to 64, and OPEN when it is below

In Vmix:
Control: ControlChange
Channel: 11 Note:11 to: 127
Event: Preview
Input: 1, Camera 1
Type: Fader

Parts
https://www.thomann.de/d...i_solutions_r8_relay.htm
http://www.midisolutions.com/progtool.htm

You will need to source a DB25 connector and Jack cables with your local electronics shop (like Conrad.de)

Good Luck Midi Solutions R8 - Hollyland Tally in Vmix user manual v1.2.zip (1,651kb) downloaded 5 time(s).