Modifying an OBDLINK SX USB Adapter for HS/MS-CAN relay managed by RTS

Discussion about adapters and connections - usage, problems, solutions
ham_op
Posts: 11
Joined: Tue Feb 05, 2019 10:51 pm
Vehicle: Ford, Escape XLT, 3.0L DOHC V6 DuraTec, 2003

Re: Modifying an OBDLINK SX USB Adapter for HS/MS-CAN relay managed by RTS

Post by ham_op » Tue Mar 12, 2019 5:45 am

@ForScan

In my 2003 Ford Escape 3.0L V6 car, with a laptop hooked up to the OBDlink SX (OBD-II port connector & USB cable are tiewrapped to prevent potential disturbance by feet on control pedals) running Win 7 Home Premium (yech McNazi$oft crap OS), some condition is crashing ForScan program, generally, but not always, when I'm running OSCILLOSCOPE and it seems that the problem appears to be a buffer over-run behavior, which is consistent with a buffer that is too small for the amount of data being streamed. I originally thought that the problem might be caused by the Ford side of the bus over-running the adapter, but now I've determined that its on the adapter side of the bus, it looks to be a hand-shake problem. However, I notice that only 12 or 13 items may be displayed, while the TABLE window displays ALL of the assigned monitor points, the OSCILLOSCOPE 'window' does not incorporate a side of window vertical scroll bar, so any monitored item beyond the bottom of the OSCILLOSCOPE screen isn't viewable. From a programmer's perspective, what should be implemented is a DASHBOARD item counter that prevents more monitors than can be displayed in the OSCILLOSCOPE window or provide an OSCILLOSCOPE scroll-bar to enable scrolling the traces up to view the below window traces. Although there does seem to be some correllation between the over assigned monitors on the OSCILLOSCOPE page and program crashes, the TABLE window when in focus also crashes the program!

Via the DASHBOARD I deassigned enough monitor points to only display 12 traces and since doing so the program has not crashed. Of course this may be simply coincidence. Only further extended operation will suggest the truth.

someone972
Posts: 3
Joined: Wed Mar 06, 2019 4:53 am
Vehicle: 2007 Ford Escape XLT 3.0L AWD

Re: Modifying an OBDLINK SX USB Adapter for HS/MS-CAN relay managed by RTS

Post by someone972 » Tue Mar 12, 2019 5:53 pm

Hmm, I suppose I could put an oscilloscope on the RTS line and see if it changes state at any time during regular use. Not sure when I'll get around to that though.

someone972
Posts: 3
Joined: Wed Mar 06, 2019 4:53 am
Vehicle: 2007 Ford Escape XLT 3.0L AWD

Re: Modifying an OBDLINK SX USB Adapter for HS/MS-CAN relay managed by RTS

Post by someone972 » Mon Mar 25, 2019 2:51 am

Took a closer look at the board today. Was able to confirm that the 5 pin unpopulated header next to the OBD port is in fact a PIC programming port for the PIC24HJ128GP502 main chip. The pin that the RTS line is hooked up to is the PGEC2 pin of the chip, so it's likely that the firmware flashing process is using the RTS signal as the data clock for the chip. It shouldn't cause any harm during normal operation to assert that pin low I don't think.

I was able to get my circuit rigged up with a DG9415DQ dual 2:1 analog switch chip. After a couple of screw ups on my part I was able to get it to work with FORscan's auto switching! Now I need to do a permanent install; breadboards hanging off of the OBD port isn't the most stable :lol:. I will hopefully be able to do a write up of sorts on how to modify the red OBDLink SX like I have it once the permanent install is done.

Microbe
Posts: 1
Joined: Sun May 19, 2019 10:53 am
Vehicle: Fiesta mk6 2006 1.6

Re: Modifying an OBDLINK SX USB Adapter for HS/MS-CAN relay managed by RTS

Post by Microbe » Thu May 23, 2019 11:18 am

someone972 wrote:
Mon Mar 25, 2019 2:51 am
Took a closer look at the board today. Was able to confirm that the 5 pin unpopulated header next to the OBD port is in fact a PIC programming port for the PIC24HJ128GP502 main chip. The pin that the RTS line is hooked up to is the PGEC2 pin of the chip, so it's likely that the firmware flashing process is using the RTS signal as the data clock for the chip. It shouldn't cause any harm during normal operation to assert that pin low I don't think.

I was able to get my circuit rigged up with a DG9415DQ dual 2:1 analog switch chip. After a couple of screw ups on my part I was able to get it to work with FORscan's auto switching! Now I need to do a permanent install; breadboards hanging off of the OBD port isn't the most stable :lol:. I will hopefully be able to do a write up of sorts on how to modify the red OBDLink SX like I have it once the permanent install is done.
Hey there someone, did you manage to get the auto ms/hs working on the new red SX ? Thanks ! interested to know.

dadams2169
Posts: 1
Joined: Sun May 26, 2019 2:14 am
Vehicle: ranger 3.0lv6 2003

Re: Modifying an OBDLINK SX USB Adapter for HS/MS-CAN relay managed by RTS

Post by dadams2169 » Thu May 30, 2019 6:13 am

someone972 wrote:
Mon Mar 25, 2019 2:51 am
Took a closer look at the board today. Was able to confirm that the 5 pin unpopulated header next to the OBD port is in fact a PIC programming port for the PIC24HJ128GP502 main chip. The pin that the RTS line is hooked up to is the PGEC2 pin of the chip, so it's likely that the firmware flashing process is using the RTS signal as the data clock for the chip. It shouldn't cause any harm during normal operation to assert that pin low I don't think.

I was able to get my circuit rigged up with a DG9415DQ dual 2:1 analog switch chip. After a couple of screw ups on my part I was able to get it to work with FORscan's auto switching! Now I need to do a permanent install; breadboards hanging off of the OBD port isn't the most stable :lol:. I will hopefully be able to do a write up of sorts on how to modify the red OBDLink SX like I have it once the permanent install is done.
someone972 im curious too did you get it all up and working and have any pics yet as i too have the red one and am ready to do this too.

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