D-sub to USB converter causes maxspeed?

Dear Sirs/Madams,

I\'m using a ax3500 with the supplied 15pin(male) to 9pin(female) d-sub cable. However as I don not have a d-sub connection on my laptop I\'m using a d-sub to USB converter cable. When I plug this d-sub to USB converter cable into the supplied (15pin-19pin)d-sub cable WITHOUT plugging the other end of the d-sub to USB converter cable into my laptop, about 1 second later m2+ (my second motor) outputs full power. However when I do plug the other end of the d-sub to USB converter cable into my laptop this problem doesn\'t occur. We tried using a different d-sub to USB cable converter but this did not fix the problem. So it seems when there is a open circuit with the d-sub to USB converter cable, somehow the ax3500 gets a signal to output full power to m2+.
Any suggestions? This problem is a serious safety issue for us.

(Note: I have a video clip of this problem; please advise me if you want to view it)

Thanks
Aran

This is strange but it may be that the adapter is issuing plulses that are translated by the controller as RC commands. Try configuring the controller in rs232 using roborun. Then save the configuration to the controller. Then try connecting your rs232 adapter

This sounds very much like the problem we\'re having with our AX2550HE. We also use a USB/232 converter. On power up, the computer takes a while to boot and the USB converter is dead. Very shortly after power up (while the computer is just barely booting), the motor controller goes to full power on both channels (see post to this thread for more).

This is also a serious safety issue for us. We\'ve never seen this before with older motor controllers.

Unknowingly, we\'ve done as Cosma suggested: using roborun to configure RS-232 mode at startup. Unfortunately, it appears that switching from modes from RS-232 to RC mode threw the controller back into this odd startup mode. (It was probably still in RC mode on the next startup.)

Any other suggestions?

Dear Sirs/Madams,

I am still having the same problem with my Serial to USB converter.

In response to cosma\'s suggestion:
It is not viable to switch the mode of the ax3500 (in Roborun) to default serial because we are intending to have the ability to switch between RC and Serial communication (hence the ax3500 needs to be set to default RC mode). Please correct me if this isn\'t true.
Any suggestions would be greatly appreciated; we need to overcome this safety issue as soon as possible.

Thanks

Aran

If you need to switch between RS232 and RC, then this is going to be a problem. It is very strange, however that your USB adapter would output any data after you PC has booted. Regardless that is sends bad info to the controller. An USB adapter should remain quite. If you have an oscilloscope, try observing the signal it outputs on pin 3. Make sure that you dont have the controller connected to the adapter and rc radio at the same time. Try yet another adapter. We will do a few more tests on our side as well.

Older controllers used in the same configuration do not evidence this problem. We never saw this happen with version 1.7 using exactly the same configuration of computers, usb/serial, etc. The system used to switch between RC and RS-232 with no problems.

Based on our experience, it seems that something new and different in the controller (firmware? microcontroller? serial port interface?) has introduced this behavior.

What changes do you think might be sensitive to USB/serial startup data? What data has to be present at the d-sub port to switch from no control to full blast?

We use a Keyspan USB/serial adapter.

The only change in this area is that the timing has been relaxed a bit so that signal would be considered lost after a slightly longer delay.

Please try running v1.7b on this controller with this adapter and report. www.roboteq.com/files_n_images/files/sof...roboup17b-021105.zip

Note that in any case, your USB adapter should be quiet.

Dear Sirs/Madams,

Thank you for your suggestions. I reverted back to the older firmware(1.7b) which seemed to fix the problem, however we would prefer to be using the latest firmware.

We are unable to access an oscilloscope to observe the signal output on pin 3 on our serial to USB converter however we did notice that when the board is in mixed mode operation this problem does not occur. It only occurs when the board is in Separate mode... So it almost appears the board is receiving RC commands to output full power to m2+ when the usb cable is in an open circuit state, but if that was the case then mixed mode would produce something similar right?

Just to reiterate the problem is that we\'re connecting a serial to usb connector to the supplied serial cable for the ax3500 and whenever the usb end of the convertor isn\'t plugged into anything we see m2 operating by itself at full power. This happens with 2 different serial to usb converters, doesn\'t happen in mixed mode or when the device is in serial mode.

Thanks

Aran

If motor2 is spinning, then it means it is picking up a signal on the RC input 2. That would be pin 4 on the connector. Try grounding this pin to see if the problem disapears. If it does, pull the input up or down with a resistor so that you can still use it as the second channel input in RC mode.