Will a PMDX-126 rev C work to replace this BOB which came with

[chaka7119]

I purchased a PMDX 126 rev c and a pmdx 107. I tried to install these boards to replace my current BOB. I could not get the install to work correctly, there was movement but very jerky and unstable, so I had to put the old one back in. I'm trying to figure out why it didn't work, I think I know why, but would like to ask for confirmation from a more experienced user, because experienced I am not. Here is why I think it didn't work. In the notes in the manual it says a 24V totem pole to GND system is incompatible with the PMDX 126 that all 24V signals must be PNP-style (I don't know what that means) where the signal is either driven to 24V or left floating (don't know what that means either). I'm assuming I have a compatibility issue here but am unsure and would like verification. Ive attached a pic of my current BOB so you can see what I'm looking at (the 24V and GND connections next to eachother).  If I do have compatibility issues are there any options that I can pursue to get myself to an upgraded BOB (PMDX 126), spindle control, (PMDX 107) and smoothstepper? Thanks for your time and help in advance.

[Steve Stallings]

Hello chaka7119,

Was the motion jerky for both keyboard jogging and for running G code?

The statement about not being able to use sensors with 24 volt totem
pole output is valid, however sensors with totem pole outputs are very
rare and it is unlikely that you have them. You probably have either NPN
or PNP standard outputs and either of those will work with the PMDX-126
when the sensor is powered from 24 volts DC. If you want to be sure, try
to find a model number and brand on your sensor and we will check on it.

There are some NPN sensors that have caused problems due to output
leakage current. If this is the case you would expect to see error messages
about hitting the limits in the status window at the bottom of the screen
if you are using Mach software.

If you have a drawing of how you wired the PMDX-126, we will be happy
to review it to make sure your wiring was correct.

Regards,
Steve Stallings
PMDX

[Bob at PMDX]

Not to step on Steve's toes...

One thing to try is to connect only your motor drivers to the PMDX-126.  Disconnect any sensors or EStop switches (and connect a jumper wire from the PMDX-126's ESTOP input to the adjacent GND terminal).  Then try jogging the machine and see how the motion is.  This will help make sure that you have the step/dir/common connections configured correctly before we go on to looking at you sensor inputs.

Also - double-check the AC input voltage selector switch on the PMDX-126.  We ship the boards with the switch set for 230/240VAC as a safety precaution.  If you are running 110/120VAC then the switch needs to be changed.

Bob

[chaka7119]

Thanks  for the replies. I've gotten a bit busy right now so I don't have time to attempt the install again, but I will here in the near future post more info about my install plan to get your opinions on my second attempt. I appreciate it