The weakest link
- blacksmith
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Platform consensus seems to be the weakest link in this great software.
Not that there is not a solution but it is illusive. In contrast:
- Linux is powerful, precise and intolerant of misconfiguration, part of what makes it a business staple.
- CNC is likewise precise and gives superb results when the rules are followed.
- The drives must have everything just right, power supplies on the money, wiring just so.
- The application software expects proper configuration as well.
I'll pay my dues and figure this out but I certainly understand the frustration on the forum.
Be patient with the next set of newbies who asks this same question again and again.
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spending days trying to shave off a few usecs here and there.
For software stepping systems (parallel port) the hosts latency may limit your maximum steprate somewhat
but unless you have a high performance drive system, you often run into stepmotor torque issues first.
There are many modern PCs that have quite adequate latency. The J1800,J1900 based CPUs have decent latency and are nice
fanless and fast systems. Some faster modern CPUs like the Intel G32XX with a decent H97 based motherboard have remarkably
low latency.
If you do have a higher performance system and move to hardware step generation or a servo system with feedback,
latency matters even less. With the right hardware, latencies is the 100's of uSec region are harmless,
so its actually not that easy to find a system the cannot be made to work
(laptops excluded, laptop CPUs often go on extended holidays when changing power modes)
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- blacksmith
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For software stepping systems (parallel port) the hosts latency may limit your maximum steprate somewhat
but unless you have a high performance drive system, you often run into stepmotor torque issues first.
I appreciate your kindness to reply. So we can assume anything off Craigslist is ok? I am only half joking.
If you do have a higher performance system and move to hardware step generation or a servo system with feedback,
latency matters even less.
I appreciate your life's goal is not to write a novel inside of a cnc forum however to my original point, it is still a bit illusive. I have a suggestion, if this is allowed. To avoid serious geek overload, petition Linuxcnc to allow vendors to post on this forum, have a section where a vendor can post a latency spec'd laundry list, say a bill-o-materials for a minimal/mid/high range system (motherboard, cpu, add-on cards, case, power supply, memory, SSD, video, etc) and they can help new users purchase the right platform for vendor's proprietary hardware first time. They sell more, and the end users get more because they are zeroed in on the solution and not the theory. If there was one part number for everything... well I digress.
Users can do the same ("pimp my PC) and list the BOM for their setup as well. We will move from theory to practice .
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To avoid serious geek overload, petition Linuxcnc to allow vendors to post on this forum, have a section where a vendor can post a latency spec'd laundry list
I think you will struggle to find a vendor interested in even selling a system with linux installed.
Likewise finding vendors even knowing about latency regards realtime kernels.
The only mentions of latency I have ever seen relate to network latency.
If someone was wanting to sell computers, tailored to use with Linuxcnc, components chosen for best latency etc, I cannot see why they would have any difficulty making their products known to the forum.
But if there is someone out there, they might have a niche market, albeit probably a 'high maintenence' one.
regards
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- kornphlake79
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I appreciate your kindness to reply. So we can assume anything off Craigslist is ok? I am only half joking.
The computer I bought on Craigslist does just fine. I believe there is a recommended system spec in the wiki somewhere, it lists a pentium 4 system. When I was looking in craigslist for an old PC to run linuxCNC I couldn't find many pentium 4 systems, a core2duo system was easier to find and cheaper or marginally more expensive in most cases. anything newer than a core2duo probably doesn't have an onboard parallel port. I haven't competed in any latency drag racing though maybe the computer I've been using without any problems isn't so great.
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- blacksmith
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I think you will struggle to find a vendor interested in even selling a system with linux installed.
Pardon my naivete but are the vendors selling the Mesa, Pico, Mechatronics and the like disinterested in at least appearing to lower the barrier of entry for potential cash customers? If linuxcnc were even slightly cookie cutter at an entry level the userbase would explode and bring their money with them.
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- blacksmith
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The computer I bought on Craigslist does just fine. I believe there is a recommended system spec in the wiki somewhere, it lists a pentium 4 system. When I was looking in craigslist for an old PC to run linuxCNC I couldn't find many pentium 4 systems, a core2duo system was easier to find and cheaper or marginally more expensive in most cases. anything newer than a core2duo probably doesn't have an onboard parallel port. I haven't competed in any latency drag racing though maybe the computer I've been using without any problems isn't so great.
The Intel naming convention requires flexibility; PCW mentioned the "Intel G32XX" which had a unit release in March of 2015. It's a Pentium.
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- Todd Zuercher
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- LearningLinuxCNC
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