5 ms·

USB serial adapters will give you a standard usb port at /dev/ttyUSBn, usable via minicom etc.

ChuckNorris89 5y ago
USB to serial/paralel adapters are good enough for most hobby projects but aren't suitable for professional or latency critical applications like industrial, audio, arcade retro-emulation and CNC machines. There's too many variables in the way, like the USB to X chip used in that converter plus the driver for it and how the OS scheduler handles the USB stack and API calls, all this causing major jitter in the communication timing. In uni we still had air-gapped Win2K/98 computers for the robotics labs since in the days prior to Windows XP, your app could write directly to the serial/paralel ports, so you could have your program use 100% CPU load, jitter-free, to poll the serial/paralel port, that's why they were used in CNC. For example your Win/DOS program would directly drive the cutting head in real-time through the paralel port. You can say goodbye to that via USB converters unless you want your expensive machine mangle its cutting head. My embedded systems prof from uni would only buy Fujitsu (Siemens) laptops as they were the only ones who still sold models with serial and parallel ports on modern hardware even as late as 2017(!), so if you're a professional or serious hobbyist in this space I suggest you grab one of those before they become scarce and overpriced like how high-end CRTs have now become. There are companies in Taiwan/China making custom X86 barebones/motherboards using modern hardware and old ports but they're low volume and destined for the industrial market so they have eye-watering prices.
- mschuster91 5y ago
  > There are companies in Taiwan/China making custom X86 barebones/motherboards using modern hardware and old ports but they're low volume and destined for the industrial market so they have eye-watering prices. Alternatively, you may take an embedded board standard like Comexpress that has a wide range of ports, including a bunch of real UART.
- _trampeltier 5y ago
  Fujitsu Siemens Notebook not just had a serial and a paralell port, they also had a 3:4 monitor (I think is the way better format for a notebook). So I bought one of the latest models :-). For industrial use Siemens has a notebook called "Field PG". It has 2xEthernet and even the newest models have a real serial port (and also ProfiBus if you need that).
  - ChuckNorris89 5y ago
    Yeah, in my book, Fujitsu-Siemens was one class above the Lenovo Thinkpads of late which are now a fading shadow of their former glory days. Check out how many ports and devices they can fit into a modern thin and light without compromising repairability https://www.youtube.com/watch?v=hS2uogVMK8U https://www.youtube.com/watch?v=hS2uogVMK8U https://www.youtube.com/watch?v=bXmlgc7Qyhc https://www.youtube.com/watch?v=bXmlgc7Qyhc
    - _trampeltier 5y ago
      I have one for private use.
- cartoonfoxes 5y ago
  > USB to serial/paralel adapters are good enough for most hobby projects but aren't suitable for professional or latency critical applications like industrial, audio, arcade retro-emulation and CNC machines. That doesn't stop their rampant use in those applications, regardless.
- deleted 5y ago
  [deleted]
- sumtechguy 5y ago
  You beat me to it. There are some good ones out there but they are rare. I have not had to do it recently so I can no longer recommend any. What is really annoying is how over the place the USB ones are in quality and drivers. The rub is they almost work. In many cases they are fine. But some of them have very odd modes of working fine then becoming jittery. What is also annoying is you can find a brand that 'works great' then the next batch they switched something out. Then there are some out there if your software does not play with the rts cts 'pins' correctly the whole thing will get out of wack. So your can end up in a condition where it works rock solid on real hardware but the USB will refuse to work correctly because you did not follow the 'standard', or worse sorta work.
- squarefoot 5y ago
  "There are companies in Taiwan/China making custom X86 barebones/motherboards using modern hardware and old ports but they're low volume and destined for the industrial market so they have eye-watering prices." Many of those small industrial grade mainboards, especially the Mini-ITX ones, are also employed in game / slot machines and have plenty of serial ports, GPIOs, etc. There's a market for used ones on Ebay and elsewhere. There also are cheap PCI-E to RS232 adapters that cost less than 10 bucks delivered, so serial ports aren't really a problem unless one needs them on a laptop. Actually there are also moderately priced Mini-PCIE to RS232 adapters, but bringing flat cables out of a laptop doesn't seem that practical.
- dekhn 5y ago
  my CNC works just fine with USB. The USB connection is only moving the gcode data, which is being pre-queued to a microcontroller (not really the scenario you're describing). You can do 99.9% of "realtime" tasks with non-realtime systems that have been carefully tuned linux systems (multiple cores, remove all daemons, tune CPU scheduler) and I think thats a much better approach than trying to prop up old tech.
  - IntelMiner 5y ago
    Devil's advocate though. Does that still work when you then overlay something like Windows 98 in KVM? A lot of the ancient software was (unfortunately) Windows centric
  - ChuckNorris89 5y ago
    Your CNC works via USB because, like you said, the microcontroller in the CNC does the motor control. What I was referring to is that in the old days, PCs would control the CNC cutting head directly via paralel port, there was no microcontroller in the middle. These setups do not work wit a USB converters.
    - dekhn 5y ago
      I keep hearing about these beasts, but I am really struggling to see that after all these years it makes more sense to use a 20-30 year old CNC instead of spending the capital to buy a new one. To me the cost tradeoff seems pretty clear, even up to replacing a $20K device.
      - mikewarot 5y ago
        If your are in a job shop, and have 50 jobs set up on the machine that each only happen a few times every year or two, replacing the controller means months to years of hell as some little tweak is going to be needed for each of those jobs as they happen. Quite often, CNC machining is not the first step in making a part. Thus scrapping a part is a very expensive, and could lose a client if it happens more than once after you "update" a machine. There are very rational, very strong incentives to be conservative with computers used in industry.
- crispyambulance 5y ago
  For serial connectivity, I always just use a terminal server (like from Perle). They're just boxes that allow you to make serial console connections via ssh/telnet over a TCP port (or if you must through a virtual COM port driver). These are used widely in datacenters to connect to switches which have serial console ports for configuration. They're not unreasonable in cost (start at like $100 for 2 ports), tons of features, and not flaky like the USB-rs232 adapters. Not so sure about latency, but throughput is fine.
- stephen_g 5y ago
  Any reason you can't just use a PCIe RS-232 card? e.g. https://au.rs-online.com/web/p/serial-boards/8988545/ https://au.rs-online.com/web/p/serial-boards/8988545/
  - the_only_law 5y ago
    I personally do for some applications, but sometime I was the portability of a laptop, but with a serial port. Some ultraruggeds do have serial ports and even less PCIe slots I believe.

USB to serial/paralel adapters are good enough for most hobby projects but aren't suitable for professional or latency critical applications like industrial, audio, arcade retro-emulation and CNC machines. There's too many variables in the way, like the USB to X chip used in that converter plus the driver for it and how the OS scheduler handles the USB stack and API calls, all this causing major jitter in the communication timing. In uni we still had air-gapped Win2K/98 computers for the robotics labs since in the days prior to Windows XP, your app could write directly to the serial/paralel ports, so you could have your program use 100% CPU load, jitter-free, to poll the serial/paralel port, that's why they were used in CNC. For example your Win/DOS program would directly drive the cutting head in real-time through the paralel port. You can say goodbye to that via USB converters unless you want your expensive machine mangle its cutting head. My embedded systems prof from uni would only buy Fujitsu (Siemens) laptops as they were the only ones who still sold models with serial and parallel ports on modern hardware even as late as 2017(!), so if you're a professional or serious hobbyist in this space I suggest you grab one of those before they become scarce and overpriced like how high-end CRTs have now become. There are companies in Taiwan/China making custom X86 barebones/motherboards using modern hardware and old ports but they're low volume and destined for the industrial market so they have eye-watering prices.

mschuster91 5y ago
> There are companies in Taiwan/China making custom X86 barebones/motherboards using modern hardware and old ports but they're low volume and destined for the industrial market so they have eye-watering prices. Alternatively, you may take an embedded board standard like Comexpress that has a wide range of ports, including a bunch of real UART.
_trampeltier 5y ago
Fujitsu Siemens Notebook not just had a serial and a paralell port, they also had a 3:4 monitor (I think is the way better format for a notebook). So I bought one of the latest models :-). For industrial use Siemens has a notebook called "Field PG". It has 2xEthernet and even the newest models have a real serial port (and also ProfiBus if you need that).
- ChuckNorris89 5y ago
  Yeah, in my book, Fujitsu-Siemens was one class above the Lenovo Thinkpads of late which are now a fading shadow of their former glory days. Check out how many ports and devices they can fit into a modern thin and light without compromising repairability https://www.youtube.com/watch?v=hS2uogVMK8U https://www.youtube.com/watch?v=hS2uogVMK8U https://www.youtube.com/watch?v=bXmlgc7Qyhc https://www.youtube.com/watch?v=bXmlgc7Qyhc
  - _trampeltier 5y ago
    I have one for private use.
cartoonfoxes 5y ago
> USB to serial/paralel adapters are good enough for most hobby projects but aren't suitable for professional or latency critical applications like industrial, audio, arcade retro-emulation and CNC machines. That doesn't stop their rampant use in those applications, regardless.
deleted 5y ago
[deleted]
sumtechguy 5y ago
You beat me to it. There are some good ones out there but they are rare. I have not had to do it recently so I can no longer recommend any. What is really annoying is how over the place the USB ones are in quality and drivers. The rub is they almost work. In many cases they are fine. But some of them have very odd modes of working fine then becoming jittery. What is also annoying is you can find a brand that 'works great' then the next batch they switched something out. Then there are some out there if your software does not play with the rts cts 'pins' correctly the whole thing will get out of wack. So your can end up in a condition where it works rock solid on real hardware but the USB will refuse to work correctly because you did not follow the 'standard', or worse sorta work.
squarefoot 5y ago
"There are companies in Taiwan/China making custom X86 barebones/motherboards using modern hardware and old ports but they're low volume and destined for the industrial market so they have eye-watering prices." Many of those small industrial grade mainboards, especially the Mini-ITX ones, are also employed in game / slot machines and have plenty of serial ports, GPIOs, etc. There's a market for used ones on Ebay and elsewhere. There also are cheap PCI-E to RS232 adapters that cost less than 10 bucks delivered, so serial ports aren't really a problem unless one needs them on a laptop. Actually there are also moderately priced Mini-PCIE to RS232 adapters, but bringing flat cables out of a laptop doesn't seem that practical.
dekhn 5y ago
my CNC works just fine with USB. The USB connection is only moving the gcode data, which is being pre-queued to a microcontroller (not really the scenario you're describing). You can do 99.9% of "realtime" tasks with non-realtime systems that have been carefully tuned linux systems (multiple cores, remove all daemons, tune CPU scheduler) and I think thats a much better approach than trying to prop up old tech.
- IntelMiner 5y ago
  Devil's advocate though. Does that still work when you then overlay something like Windows 98 in KVM? A lot of the ancient software was (unfortunately) Windows centric
- ChuckNorris89 5y ago
  Your CNC works via USB because, like you said, the microcontroller in the CNC does the motor control. What I was referring to is that in the old days, PCs would control the CNC cutting head directly via paralel port, there was no microcontroller in the middle. These setups do not work wit a USB converters.
  - dekhn 5y ago
    I keep hearing about these beasts, but I am really struggling to see that after all these years it makes more sense to use a 20-30 year old CNC instead of spending the capital to buy a new one. To me the cost tradeoff seems pretty clear, even up to replacing a $20K device.
    - mikewarot 5y ago
      If your are in a job shop, and have 50 jobs set up on the machine that each only happen a few times every year or two, replacing the controller means months to years of hell as some little tweak is going to be needed for each of those jobs as they happen. Quite often, CNC machining is not the first step in making a part. Thus scrapping a part is a very expensive, and could lose a client if it happens more than once after you "update" a machine. There are very rational, very strong incentives to be conservative with computers used in industry.
crispyambulance 5y ago
For serial connectivity, I always just use a terminal server (like from Perle). They're just boxes that allow you to make serial console connections via ssh/telnet over a TCP port (or if you must through a virtual COM port driver). These are used widely in datacenters to connect to switches which have serial console ports for configuration. They're not unreasonable in cost (start at like $100 for 2 ports), tons of features, and not flaky like the USB-rs232 adapters. Not so sure about latency, but throughput is fine.
stephen_g 5y ago
Any reason you can't just use a PCIe RS-232 card? e.g. https://au.rs-online.com/web/p/serial-boards/8988545/ https://au.rs-online.com/web/p/serial-boards/8988545/
- the_only_law 5y ago
  I personally do for some applications, but sometime I was the portability of a laptop, but with a serial port. Some ultraruggeds do have serial ports and even less PCIe slots I believe.