BenQ projector control

[eric]

Hi everybody.

I'm having some issues getting the serial port on my BenQ MP620 working properly.
I have gotten a whole bunch of information right from the BenQ support team but I still am having issues, maybe somebody who actually has hooked up a serial port control system rather then just reading about it (it seems all they do) could help me.
So, this is what I know: my projector is an 8 pin mini din serial port. From what they've sent me (see attachments) pin 2 on the DB9 goes to pin 7 of the mini din, 3 to 1 and 5 to 4. I have made a cable to do this. It's about 20 feet long cat-5e. on the DB9 side my connector has labeled pins, the mini din doesn't. however pins 4 and 7 are in the middle so they are easy. Pin 1 is the only one I'm not 100% sure of, but from every diagram I have found it seems to be correct.

Ok, so the cable is made and hooked up. Now onto the control side. In the end I will be using Linux for my control box, in the mean time I have Windows/OSX/Linux all available for testing.
I initially tried using minicom for my control, but I couldn't get anywhere. So I jumped to Hyper Terminal and tried that. I was told by two different support reps two different baud speeds, 19200, and 115200. I tried both of them and got nothing.

I downloaded the two projector software programs I found on this website but couldn't get those working either.

If anybody has anything I can try I would be more than willing to give it a go.

Thanks very much
-Eric

[NdEd]

The document at http://www.fullcompass.com/common/fi...232%20Code.pdf might help.

If you can't get it to work with Hyperterminal, you really have no hope of making it work with the GUI's that Shayward and I have given to the community.

[daver2]

Couple of things I noted.

1) The document referenced by Ed shows RTS (Request to Send) and CTS (Clear to Send) present on both the projector and the PC but the pin configuration Eric has referenced has only connected up the Tx, Rx and GND pins. If your Linux box is expecting hardware handshake (RTS/CTS) and you haven't wired it up then it will not transmit anything! It is possible to disable this feature in Linux but - to be on the safe side) strap a wire link between pins 7 and 8 on the DB9 at the PC end. As the projector also has RTS/CTS I would be tempted to strap pins 2 and 5 of the projector connector also.

2) Shield (the shell of the DB9) and Ground (GND) are not the same thing. Pin 5 of the DB9 should be connected directly to pin 4 of the projector. The metalwork (screen) of the DB9 should be connected to the metalwork of the projector.

With the projector disconnected and a tempory shorting link fitted between pins 1 and 7 of the connector that plugs into the projector - you should be able to fire up hyperterm (doesn't matter what baud rate) and it should echo whatever you type on the PC's keyboard. This proves that hyperterm, the PC serial port and your cabling is correct. Remove the shorting link and hyperterm should stop echoing what you type (this proves that the last test did really work and it wasn't echoing by luck!)

Connect up the projector and select whatever baud rate is in the manual. Ed's document suggested 115,200 bps with 8N1.

Ed's document suggested that plain old ASCII can be used to command the projector - but it was interesting that the command string was started and finished by <CR>. Check that hyperterm has not got the "auto linefeed" option set (this could be confusing the projector if it is only expecting <CR> and not <CR><LF>).

Let me know how you get on or (if the above doesn't work) I may have some more ideas for you to try.

[eric]

Hi again
I guess I should turn on email notification, I still have gotten nowhere, but I forgot about this thread.
Daver you said

The document referenced by Ed shows RTS (Request to Send) and CTS (Clear to Send) present on both the projector and the PC but the pin configuration Eric has referenced has only connected up the Tx, Rx and GND pins. If your Linux box is expecting hardware handshake (RTS/CTS) and you haven't wired it up then it will not transmit anything! It is possible to disable this feature in Linux but - to be on the safe side) strap a wire link between pins 7 and 8 on the DB9 at the PC end. As the projector also has RTS/CTS I would be tempted to strap pins 2 and 5 of the projector connector also.

Did you mean basically a loopback in the db9 itself? as well as in the projector. Not hooking the projector pins to the PC?

[simchurch]

Hi all, just a note that Ive managed to get the benq working, the key is to connect all the pins exactly like in the benq sheet that NdEd sends above here. Just connecting the 3 that Eric mentions wont do it.
Good night, and..

[daver2]

Welcome back Eric!

First - some basics. There are two modes of handshaking on serial ports (1) hardware and (2) software (sometimes called XON/XOFF).

HARDWARE HANDSHAKE: The RTS signal (Request To Send) is signalled when one end wants to transmit - but nothing is actually transmitted until a Clear To Send (CTS) is received. The character(s) are then transmitted until CTS is removed.

SOFTWARE HANDSHAKE: The RTS and CTS signals are ignored! Two special characters are transmitted between the communicating devices to prevent buffer overflows.

So - what can go wrong. If you wire the hardware handshake pins up and one end is expecting to use hardware handshakes but the other isn't then it wont work. If you wire the hardware handshakes up and neither end is expecting to use this means of handshaking it will work - but you risk overflowing buffers in one or both devices (i.e. the link can become unreliable).

Experience from simchurch (and the BenQ document) implies that you should wire the cables up as per NdEd's link. However, you then have to make sure that the serial port on your PC is correctly handling and generating the hardware handshake signals.

The information you have been told (to wire GND, TX and RX) implies that the projector does not use hardware handshaking itself and the assumption is that the PC is not expected to either! This may be an incorrect assumption.

I would suggest the following:

Make up the cable as per NdEd's link (with the hardware handshaking connected). Use Hyperterm on your PC (or similar). Try and communicate with the cable connected to ther PC but the projector disconnected. Type characters on your keyboard - you shouldn't get anything echoed back! Fit a shorting link between pin 1 (RX) abd 7 (TX) at the projector end of the cable (remember - with the projector disconnected). What happens if you type on your keyboard now? If you get an echo - your PC is not configured for hardware handshaking (pins 2 and 5 are not connected at the projector end). If you don't get an echo - try shorting pins 2 (CTS) and pin 5 (RTS) at the projector end of the cable (still with the projector disconnected). Irrespective of the baud rate etc. you should now get an echo when you type on your PC keyboard. This procedure proves the cable and proves if hardware handshaking is used/configured on your PC.

Remove the shorting links and connect the projector. If you have access to an RS232 breakout box with LED monitoring you should be able to insert this between the PC and cable and check that the PC is actually transmitting characters in response to the PC keyboard.

Try this and let me know how you get on.

WARNING. Please double-check with the available documentation the pin numbers and functions in my description above. I may have accidentally got something wrong in which case placing shorting links on a serial port could damage your equipment. If in doubt STOP, THINK, ASK.

Dave

[eric]

Thanks everybody for the help, however I still have gotten nowhere and am about ready to give up.
I have made my cable exactly like the document that NdEd gave, and followed it exactly, no dice.
I have not been able to short the pins in my cable as I can't find anything small enough to fit into the connector short of soldering small jumper wires into it temporarily, I have however used my multimeter and checked, rechecked, and checked again my connections and corresponding pin numbers.
Simchurch, did you connect the pins like it says as well as use the settings? 115200/8/N/1 with no Flow Control.
After reading what Dave suggested (which I have tried as best I can) that document seems to not make sense to me, it says use the hardware flow control pins and connect them, but turn off flow control.
This is nuts, I have recently (last week) built a serial interface for my Roomba and it works perfectly first try, but my projector just has to be difficult.

I do not have access to an RS232 breakout box so that won't work for me.

Maybe I'll just fallback and use IR signals, however since I've lost my remote I would need to find somebody willing to record them into an LIRC file for me.

Thanks everybody
-Eric

[daver2]

Eric,

Your right about the flow control in the BenQ manual - didn't see that one myself. It's nuts as you say! This statement alone implies that you can hit the projector at the full rate of the serial line and that the projector itself does not use hardware handshaking control (i.e. TX, RX and GND should be sufficient to get a working link).

'fraid I've got no more suggestions regarding the hardware cable (sounds like you've done everything you can). One further suggestion though would be to check through the manual to see if there are any configuration menus for the serial port. Long shot - but I have occasionally seen configurable protocols.

Can anyone else chip in with other suggestions for Eric?