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Joe. Thanks a lot for your help and advice into this. Sorry I didn't replied before, but after finishing the M90 coding I had a loads---t of due tasks to complete. The M90 is doing OK now, had to install an encoder to feedback the position and install a separate 24v line with a backup battery to keep the programs alive. At least the machine is up and running now. I'm ordering next week a SM70-J-T20 to have a definitive solution. 400hz is the most I need to drive the motor at the desired speed. I'm very pleased I found unitronics PLCs time ago. By far they have the most intuitive coding platform. Developing applications with them is very swift. Again thanks a lot for your help.

Thanks a lot for your reply. You were pretty right on your first reply about using this such model... Now I just found that the backup battery does not retain the variable data after a power cycle.... and I only realised at the very end of the project. Obviously is my complete fault as I only did a quick check on the online help and lost the detail about the database not being backed up. Now that I'm really screwed, does the Samba models do retain all the variable and database parameters? Which model will be the Samba alternative with a proper PWM output? Thanks again for your help.

Hi Joe Thanks for your quick reply. I,m just retrofitting an old dough lamination machine. The stepper motor just controls the lamination roller height, so precision or speed is not paramount. I had this M90 stuck on a shelf for years, and when the machine controller broke down last week, it was the most suitable thing at hand for a quick fix. I,m about to finish the program. Worst case scenario I will use the analog out linked to an arduino to provide the pwm, and read the pulses with the high speed input. As I told precision is not key here, so some missing steps up or down during the program doesn't make a difference. I will send the roller to the home position after every complete cycle to reset the position. If it goes OK, with more time I will implement into a SM70-J-T20 , so I can retrofit all the three machines on site. Other I/Os are just some sensors and relays, no rocket science here. What about that interrupt routine? Do you have any example? Thanks in advance for your help. Is something like this:

Hi all Just starting a fight with a M90-TA2-CAN PLC. I need to control a stepper motor driver with this. I see there is no PWM output available on this model, so I will try the approach of using a timer to flip the port status and create the pulse stream. I only find a 10ms timer as best, and I´m worried that is not fast enough to drive at the speed required. Most likely I´m not using the right approach here. Any other ideas?