pda cable to laptop cable with this cable, get all that? STEVE THE WISEMAN I NEED YOU

1gcrazy · 02-09-2007, 11:42 PM

Ok guys, I've been searching and searching. I'm trying to make a cable to turn my ordinary PDA datalogger cable into a laptop datalogging cable. I've already got the pda cable to work with the pda. Except my palm is out of service at the moment. So in a desperate attempt to try and read this code i'm trying to make this cable.

I've been looking at posts mostly by Steve the wiseman and he said to make a null modem adapter and a gender changer. I added them together and this is what I came up with.

The first picture is the schematic I used to build my null modem adapter. I didn't add any resistors or anything because I figured that the PDA cable already has them and I just needed to swap where each wire went which is why I built the NMA.
Anyways, I went out and tried it with MMCD and a palm emulator and I know the emulator works great but I can't get the damn thing to sync to my car. I just keep getting serial port error or whatever it says.
Anyways, It would be MUCH apreciated if I could get some guidance here.
Also, I didn't connect any other wires except the 3 that they listed to connect.

Thanks in Advance!!!

1gcrazy · 02-10-2007, 02:25 AM

I have a feeling the indicated resistor is going to hang me up because even if I swap p2 and p3 i'm still going to have that resistor on p2 when it needs to be on p3 during the laptop logging. I hope i'm making sense.

Essentially this is what i'm trying to accomplish:

I want to keep my cable coming off the diagnostics port there all the time and beable to plug in my PDA datalogger cable OR my LAPTOP datalogger cable quickly. Is this doable? I dont want to cut into the cable coming off the diag port.

SinaiTSi · 02-10-2007, 08:05 AM

Are you in a sense just trying to make a null modem adapter/gender changer in one?

1gcrazy · 02-10-2007, 08:37 AM

I guess so. I'm really getting frusterated....I've re soldered this thing twice and burnt the crap outta my hand yesterday. I can't see where i'm going wrong in the wiring....??

SinaiTSi · 02-10-2007, 11:08 AM

I work for an A/V company and about 90% of our job is wiring up control systems etc. Whenever we make a null modem adapter we use pins 2,3,5 and 7 and 8 too. Try that, but swap those too, 7 goes to 8, 8 goes to 7. Let me know if that works. So we do:

2-3-5---7-8
3-2-5---8-7

steve · 02-10-2007, 11:54 AM

If you look closely at the schematic you'll see that the only difference in wiring between the two is how pins 2 and 3 are connected. Physically the connectors used are different sex and so the pin order reverses on the connector. The diagram you have make that same error. If your looking at the back of the connectors the female is numbered left to right like above (so the picture above is labled wrong) and the male is right to left

So to take a cable that was for a PDA and make the adaptor to connect to a PC you need to have two female DB9 connectors and wire pin 2 on one to pin 3 on the other, then pin 3 on the first to pin 2 on the second, followed by pin 5 to pin 5.

The part you have circled is a diode not a resistor. Diodes block current from flowing in one direction while allowing it in the other direction. In this circuit it allow us to combine both the transmitted and received data from the logging computer onto the single pin on the ECU.

Steve

SinaiTSi · 02-10-2007, 12:30 PM

Yeah, I forgot to add that. It is very important to look at the numbers on the back of the connector. Some people will just try to remember how the wiring goes from left to right depending on if it's male or female but I never pay attention, I just look directly at the numbers themselves to wire up my control cables. Some control calls for pins 7 and 8, some don't. I'm not sure about this application to tell you the truth, but make sure that you have them going to their correct numbers and if the cable still doesn't work, try using pins 7 and 8. Good luck.

steve · 02-10-2007, 02:00 PM

Pins 7 and 8 on the DB9 connector are used for hardware handshaking (RTS and CTS)
The datalogger cable doesn't use them so worst case if your PC requires them you can just loop 7 to 8 on the connector you plug into your PC.

http://www.zytrax.com/tech/layer_1/c..._rs232.htm#db9

Note that this picture is referenced looking into the pins from the front or a male connector not the rear where the wires attach.

Steve

1gcrazy · 02-10-2007, 02:01 PM

Quote:

Originally Posted by SinaiTSi

I work for an A/V company and about 90% of our job is wiring up control systems etc. Whenever we make a null modem adapter we use pins 2,3,5 and 7 and 8 too. Try that, but swap those too, 7 goes to 8, 8 goes to 7. Let me know if that works. So we do:

2-3-5---7-8
3-2-5---8-7

Ok, i'll try that. I'm sure it wouldn't hurt. So swap 23 and 78 and 5 is constant. Got it.

Quote:

Originally Posted by steve

If you look closely at the schematic you'll see that the only difference in wiring between the two is how pins 2 and 3 are connected. Physically the connectors used are different sex and so the pin order reverses on the connector. The diagram you have make that same error. If your looking at the back of the connectors the female is numbered left to right like above (so the picture above is labled wrong) and the male is right to left

So to take a cable that was for a PDA and make the adaptor to connect to a PC you need to have two female DB9 connectors and wire pin 2 on one to pin 3 on the other, then pin 3 on the first to pin 2 on the second, followed by pin 5 to pin 5.

The part you have circled is a diode not a resistor. Diodes block current from flowing in one direction while allowing it in the other direction. In this circuit it allow us to combine both the transmitted and received data from the logging computer onto the single pin on the ECU.

Steve

Ok I think I followed all of that. I did pay special attention to the orientation of the numbers. I'm posting picture of what I have here. Since blue is my favorite color, its connector A. B is for Connector Black.

Please, on the upclose backside pictures of the connector, note that the difference in connectors is Blue vs Black. Pin 5 is the Blue wire. Pins 2 and 3 are the red and black wire. It was easy to understand the red and black because I always think of red as dominant over black because of power vs. no ground on car batteries

ANYWAYS, i'm almost positive that my soldered cable is good. All my soldered points are good. I've checked to see if there are breaks in the wire and I dont see any. I could get a whole new sleeve and make my own cable with wires and use that to verify that the wires are solid. I did use this cable from my old palm to db9 cable so it COULD be faulty but i'm 99.8% sure the reason the palm to db9 cable failed was in the connector.

So there it is...

steve · 02-10-2007, 02:47 PM

That should work fine. I haven't run MMCd under the emulator on a PC so I can't provide much help there and your problem can just as easily be with using the serial port under the emulator as with the cable.

Steve

1gcrazy · 02-10-2007, 03:00 PM

Quote:

Originally Posted by steve

That should work fine. I haven't run MMCd under the emulator on a PC so I can't provide much help there and your problem can just as easily be with using the serial port under the emulator as with the cable.

Steve

So try and switch the emulator to accept the serial connection?

1gcrazy · 02-10-2007, 05:33 PM

I'm not having very good luck with this...

1gcrazy · 02-10-2007, 05:44 PM

Ok i just enabled the palm desktop to communicated with the serial port and i get a rather long message but the gist says: "The emulator could not open COM1" I'm a bit baffled WHY?!

SinaiTSi · 02-10-2007, 06:33 PM

You can always buy a null-modem at radio shack and see if the problem lies within your cabling. Even though your connections look good, so I sorta doubt it but it doesn't hurt to always check.

steve · 02-11-2007, 12:35 AM

Quote:

Originally Posted by 1gcrazy

Ok i just enabled the palm desktop to communicated with the serial port and i get a rather long message but the gist says: "The emulator could not open COM1" I'm a bit baffled WHY?!

Maybe some other application is using it like the hotsync manager?

1gcrazy · 02-11-2007, 03:03 AM

Quote:

Originally Posted by steve

Maybe some other application is using it like the hotsync manager?

Wow as simple as that huh...I got it working. I got a code 44 which is ignition module/coil. Changed both with known working components now ive got a few other issues to investigate.

THANKS STEVE! I OWE YOU ONE!