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I want to connect a 15 pin vga output from a computer to a TV input. However I do not want any data from the TV sent back to the computer. What I mean is that I do NOT want the TV to be a smart monitor but rather a dumb one. In other words the communication will be half duplex one way (from computer towards monitor ONLY).

I looked at the pin outs & I suspect pin 12 could be the problem as it is named bi-directional data. I am not sure if this is or this is NOT the ONLY problem pin. But just wondering.

Also I am not sure how a typical cable (15 pin) is connected. Of course I could open the connector and look inside but if you know the pinout diagram anyway, there is no need to do that. I googled and it shows 15 pin several connections such as one for RGB or one for VGA and this is why I am not sure.

My dilemma is that this is a high security computer and if the computer detects any feedback from the monitor, because that info gets sent back to the server and I am screwed for security violation bigtime & I do not want to get written up or even fired LOL

Of course I can buy a dumb monitor but since I have two extra TV's I want to rather use them. These are just new digital TVs but not so new as these are not smart TVs like a WIFI-TV or roku TV or something.

user13111321
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  • connect RGB 1, 2, 3, grounds 6, 7, 8, 10 and sync 13, 14 ..... it is not RS232 cable, that is for serial comm .... i also doubt that you can buy a "dumb monitor" ... all monitors send some plug and play info – jsotola May 26 '20 at 02:36
  • Ok you are correct. I don't know why I said rs232. Anyway so I am correct in saying pin 12 is not connected ? So via which pins does the monitor send back data ? What data ? – user13111321 May 26 '20 at 03:18
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    "Half duplex" doesn't mean what you think it does. The term you're looking for is "simplex". – Dave Tweed May 26 '20 at 03:39
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    To get any *useful* display you're going to have to tell the PC's operating system and video drivers about the fact that a monitor is connected, and what sort of display mode it supports. Typically this is done via an I2C like protocol over two wires on the VGA cable, though there can be ways to force a mode without that. But either way, to get a useful display you are going to have to do things that sufficiently detailed monitoring software could see. So this is really an issue where you need to work out a solution with your employer, not a technical problem. – Chris Stratton May 26 '20 at 03:47
  • I stand corrected again. You are right. It is simplex – user13111321 May 26 '20 at 03:50
  • As for Chris's & Jsotola's comments :- it is not clear which of the stated pins are used to send back data to the computer. According to him, the monitor pins 4,11,12 & 15 are NOT connected . Pin 13 & 14 are sync signals (clearly ONLY an output from PC with no feedback to PC). Pins 1,2,3 are also RGB output only from PC. So where is the feedback to the PC ? I don't see it, unless the monitor pins 4,11,12,& 15 are connected – user13111321 May 26 '20 at 03:59
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    Get a useful display by any means and that fact will be known to system logs and system log monitors. **You have a people problem, not a technical problem.** – Chris Stratton May 26 '20 at 04:23
  • But what display are you allowed to connect the high security computer? Wouldnt the security software detect the absence of that display? – mguima May 26 '20 at 04:37
  • Chris, The basic premise of my posting is not using a computer monitor but how to use a TV monitor as a computer monitor. I am aware of the fact that I can use a computer monitor. I stated that in my first post. Additionally I am yet to hear from you or jsotola as to which pins are used to send back data (such as monitor model, which I have doubts) to the computer. I am not being difficult or mocking you but just asking a simple explanation. Thanks – user13111321 May 26 '20 at 04:47
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    Your question makes no sense - why do you think a computer monitor would be permitted and a TV not? You seem to be imagining a difference which simply is not there as something that correlates to TVs vs monitors. As before, you need to pursue this with your employer, it is not a technical problem but rather one of policy - if there even is a problem at all. – Chris Stratton May 26 '20 at 04:57
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    The solution is simple, ask Security for permission to use a different monitor. If they say it's OK, do it. If not, don't. I could tell you how to 'hack' the cable to get around possible security restrictions, but I don't want to be responsible for what they might do to you when they find out... – Bruce Abbott May 26 '20 at 06:17
  • Does your screen has a VGA input or is it separate R/G/B? Is it an high definition screen or a analog-style TV? – TEMLIB May 26 '20 at 08:59
  • "Does your screen has a VGA input or is it separate R/G/B? Is it an high definition screen or a analog-style TV?" What I am using is a digital TV not old analog. The TV accepts 15 pin VGA output. One of these TVs has provisions for 3 RGB inputs as well – user13111321 May 26 '20 at 13:39

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A standard PC will use that bidirectional data pin for detecting display presence and for determining what resolutions it supports. If you omit that pin, the PC most likely is not able to even detect when the display gets plugged in, or if it can detect that, it won't be able to determine what resolutions it supports. So most likely, there will be no picture. Not unless you have a professional video card whose drivers support forcing the interface enabled with fixed resolution, so it will output a picture even if display is not present.

Justme
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