Will this work?

[home777]

Good morning,

We have an NEC VT700 projector in a ceiling installation in our church. Currently, the projector can only be controlled by standing near the podium and pointing the IR remote at the unit. I would like to change this to control it from the back of the room.

I have installed on my laptop the NEC PC Control Utility Pro 4. It is listed as compatible with the VT700 projector.

Next, I have run a 100' DB9 cable between the sound booth and the projector through the ceiling. At one end, I am planning to buy a round DIN 8P to DB9 adapter recommended by NEC. AT the other end, I plan to use a DB9 to USB adapter.

Can someone tell me if this sounds like it might work? I'm mainly concerned about going from DIN 8P to DB9 to USB. Does anyone have experience with this, or a similar situation?

Thanks!
Russ

[prochlea]

I'm mainly concerned about going from DIN 8P to DB9 to USB.

I don't see any reason this won't work. The DB9 to DIN 8P is merely an adapter... like RCA - 1/4" or something. The USB-DB9 usually doesn't have any problems, but I've had issues with some brands over the years. I've found the most success with the Keyspan one... It's not the cheapest but it almost always works.

[daver2]

Russ,

You say you have run a 100' cable to the projector. Any idea what type of cable you are using? RS-232 serial communications is not the best in the world for communicating long distances - although this depends on the data rate, electrical noise and the physical type of transmitter and receiver. Unfortunately, there are too many variables here to say if your configuration will work or not. Since you have already run the cable - I would suggest trying it and if it works fine. I don't see any problems in converting USB to serial at the PC end and connecting it to the projector at the other. The only thing to watch is to ensure that you wire any hardware handshake lines up (if they are used).

If the length of cable is too long and it doesn't work - or it works intermittently - one solution would be to change the RS232 serial line at the PC end into RS485 and back again from 485 to 232 at the projector. There are commercial units for this conversion. The attraction of RS485 over RS232 is that it can be transmitted over much longer distances as it uses differential signals.

If all this sounds too techie - google RS232 and RS485 on the wikipedia site. RS232 is claimed at 50' nominal and RS485 at 4000' - although (as I have said) results will vary.

[prochlea]

RS232 is claimed at 50' nominal

the distance you can run varies by the speed you're running at. Alot of AV stuff runs at 9600, which I've run over 100' no problem... the faster speed you're running, the shorter the distance.

[home777]

Hi Pat and Dave,

Thank you so much for your fast and extremely helpful info. I had no idea where to look for this kind of info. Perhaps I was hasty to get my 100' DB9...we shall see. With your info, I think I'll get the two adapters and just see if it will work.

Thanks again so much!
Russ

[home777]

Originally Posted by daver2

one solution would be to change the RS232 serial line at the PC end into RS485 and back again from 485 to 232 at the projector.

The 232 to 485 converters appear to be $45/ea.; I'm assuming I would need two, one for each end?

As a possible alternative, I came across a 232 to Cat 5 converter for $50. (I would post the URL, but the forum won't let me embed links until I have reached 15 posts. The converter is at Monoprice.com, product ID 3598.) This converter includes both the local and remote units. Would this be a better solution, if I can just run a Cat 5 cable in between the projector and sound booth?

Thanks!
Russ

[prochlea]

I'd give it a shot with what you have. I think it will work. Can you get to the projector and just hook the cable up and try it out without actually running the cable?

[home777]

Yep, I think you're right. I will just try it first with the 100' 232 cable and see what happens.
Thanks!
Russ