Yesterday I spent most of the day prepping the power supplies for when the Gecko driver arrived. After cleaning out the cabinet of all the old electronics (I left some of the old cables, like the axis cables and the ones for the ATC mechanisms since I don't know yet how to handle that) I re-installed the shelf that the power supplies had been on and started doing some wiring for it. I had also left some of the old terminal strips and the conduit/wire loom and took advantage of those. I took an old construction grade heavy gauge extension cord and removed the socket end, then stripped the ends to attach to one of the terminal strips as a take off for main power supply. I then routed the original cable from the smaller PSU back to the main terminal strip and connected everything up, plugged in the main, and both PSU's fired up.
One thing about the smaller power supply--the labeling calls for 170-250VAC as input. I wanted to get away from using 240V so I decided to use 120 on it and see what happened. I don't know if it will ultimately damage the PSU, but I checked the outputs--the 5VDC read a steady 5.02V and the 12VDC read a steady 11.98V. The 48V PSU had a pair of terminals that you could short to convert it to the lower input power so that wasn't a problem. After I got them working I wired up the two cabinet door fans and all three axis motor fans to the 12VDC supply (using the old terminal strips again) and plugged in the main power. All 5 fans came to life just fine, and with those all running I checked the voltage at the small power supply terminal--it was 11.95, barely moved from the unloaded state. Well, if anyone can tell me if this is not good for the small PSU (being fed a lower incoming voltage than called for) I will have to come up with an alternative, but so far so good.
This took me most of the morning, but the Gecko still hadn't arrived so I concentrated on setting up LinuxCNC and ran into a problem with it right away. The problem is not Linux, but the PC box itself--I don't know if this is why I had abandoned it earlier but possibly. LinuxCNC includes a latency test that checks for any jitter in the system that would affect the pulse timing. Even though the version of Linux that's paired with LinuxCNC is a real-time OS, apparently there are things that go on in the bowels of any given PC that can still cause latency, so the utility runs for a while and checks for what the minimum time between pulses is needed in order to account for the jitter and not have any lost pulses to the motors. The jitter was so high that the highest speed I'll be able to get from the motors is about 36 IPM, and that's not nearly good enough for me--it's not even near the original 100 IPM the machine was capable of. So I will definitely have to do something else--either find another PC with better performance, or go with an external motion controller, which I suspect will be the best alternative. The reason I'm not sure this was the same problem I had with the PC way back when is because with my router I was using 1/4 microstepping on the drivers, and the Gecko uses 1/10 microstepping. The number of pulses needed were only 40% of what the Gecko needs, so that alone would be enough to speed up the motors considerably. I think there was some other problem that I had when using it for the router, like memory issues, which only highlight further how bad this PC will be.
The G540 finally arrived about 3 in the afternoon, and for a product that has such a high regard in the CNC community I'm a bit underwhelmed by the fact that you're required to do a complete Dsub connector assembly for each motor. I don't know what's wrong with using screw terminals like just about everyone else. Sure, the Dsub connector (if done properly) is a really nice way to connect and disconnect the motors, but how often does a person need to do that? Well, in spite of not being an electronics expert I'm really quite good at soldering, so I expect to be able to make a good, secure connection. I decided to call it a day and tackle it the next day (today), but I'm not sure I'll be able to get to it today. Being a dyed in the wool nerd I have no interest in the Super Bowl, but I do have other chores to attend to (like getting a new TV after our 12 year old Sony gave up--maybe I'll get a good deal on SB Sunday).
I will attach a couple of update photos, even though there's really nothing of interest to see, but maybe it will be interesting to someone else.
Until the next time.....
Dan