Checksum Error Detected when connecting to an S-Drive using Curtis Program

[NJChevyGuy]

I’m trying to reprogram an S-Drive 45amp controller from a mobility scooter.

I assembled cables, as per the recommended connections using FTDI FTS232-RL chips but get a “Initialization of communication interface failed, Checksum Error Detected” message using either 1314-4401 or 1314-4402 software. The error box pops up when I try to connect, after a few seconds attempting the connection.
I tried both the 3.3v and the 5v signal versions with the same results. Using FD_prog, VID/PID is set and TX/RX are inverted, and the regedit change for IAL is entered after a first attempt with the 4402 software. OEM Level is recognized as the default.

I’ve tried various COM ports with both Serial and Enhanced Serial. With Serial it sees the cable. I tried both 33k and 47k ohm resistors, and both the Curtis 4402 1309 USB 10/20/2010 v2.8.2.0 drivers and the newer FTDI 07/12/2013 v2.8.30.0 drivers.

Using either cable with the FTDI factory default settings, I can connect and reprogram the controller using the PG Drives PC Mobility Programmer 14.6.0 “Dealer” software. The parameter changes work fine, but I want to access more than the Dealer parameters. I’ve also tried using the “Checksum Correction” feature of this software, with no difference. This software will not work with inverted TX/RX signals.

FYI: I get the exact same results with either the 3.3v or 5v cables, and with either the 33k or 47k resistors. The software will not connect to the cable if I reverse the diode or if I remove the resister connection to the 5v Vcc USB line. I get the same results with Windows 7 or Windows 10.
I did NOT use the suggested Molex connections in the “$25 Windows 10 x64 OEM mode 1314 and DIY Cable” thread. They are incorrect. I used #1=Black, #2 Not Used, #3 & #4 tied together for TX/RX.

Questions:
#1: Is it safe to assume the controller is OK and its TX/RX ports are working properly since the older PC Mobility Programmer software works perfectly, the scooter runs perfectly, and those changes work as expected?

#2: Is it safe to assume all of my cable connections have been confirmed by #1 working fine?

#3: Is the checksum being verified from within the S-Drive controller (not from within the FDTI cable parameters)?

#4: Can I set the PC Mobility Programmer software to a high level than Dealer?

[NJChevyGuy]

NEVER MIND!!!!

burgerman on the WheelChairDriver forum explain that Curtis is not the same company as Curtiss, so the software is not compatible with the S-Drive controller.