The Oddy pan indexer had operator issues. The current hmi was hard to operate and was very cryptic for most people at the plant. I asked to replace it with another hmi and because of the proprietary plc/hmi system it had, this would also require a new plc. It was OK'd and I ordered, install, and programmed the new system to work with this machine. This section of the machine had a new challenge for me, it needed to control two VFD's speed and run commands. The run/stop command was easy as it was setup as discrete outputs. The speed on the other hand was 0-10v analog out via the VFD's own supply. So, setting up the analog card to act as a potentiometers was a little tricky. The first VFD was running the same direction all the time, but changed speed as dictated by the HMI. The second VFD direction was determined by position sensors and the speed was determined by the HMI.
This machine became trickier to program as the second VFD's motor has a shaft-mounted brake that was failing. So, the system was overrunning the last stop sensor quite often. I had to setup more programming tricks to get the motor to stop were it was supposed to stop. This meant running the motor for x time and then slow to a crawl until the sensor is seen. This was the viable solution and told the boss that a new brake is needed because this is not a servo system. And if they wanted a servo system, the cost of the retrofit was going to be MUCH higher than replacing the brake.
Other than the brake issue, we now had less downtime due to operator error.
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