Date   

Re: Long serial cable issue

Mark Griffith
 

Good old time research data.  Thanks for posting.

Also, people today tend to forget that most communications now is serial.  The SATA drive on your computer, serial, your WiFi connection, serial, USB 3.0, serial, etc, etc.  Just much faster than the old 9600 baud serial line to a mainframe computer.

I remember when the old IBM-PC and the early personal computers struggled to download data at speeds of 9600 baud because the CPU was just not fast enough. We have come a long way with serial data.

Mark
KD0QYN


On Tuesday, January 26, 2021, 5:09:57 PM CST, ve3smf via groups.io <ve3smf@...> wrote:


RS232 physical properties

The RS232 standard describes a communication method capable of communicating in different environments. This has had its impact on the maximum allowable voltages etc. on the pins. In the original definition, the technical possibilities of that time were taken into account. The maximum baud rate defined for example is 20 kbps. With current devices like the 16550A UART, maximum speeds of 1.5 Mbps are allowed.

Voltages

The signal level of the RS232 pins can have two states. A high bit, or mark state is identified by a negative voltage and a low bit or space state uses a positive value. This might be a bit confusing, because in normal circumstances, high logical values are defined by high voltages also. The voltage limits are shown below.

 

 

RS232 voltage values
Level Transmitter
capable (V)
Receiver
capable (V)
Space state (0) +5 … +15 +3 … +25
Mark state (1) -5 … -15 -3 … -25
Undefined -3 … +3

 

 

More information about the voltage levels of RS232 and other serial interfaces can be found in the interface comparison table.

The maximum voltage swing the computer can generate on its port can have influence on the maximum cable length and communication speed that is allowed. Also, if the voltage difference is small, data distortion will occur sooner. For example, my Toshiba laptop mark’s voltage is -9.3 V, compared to -11.5 V on my desktop computer. The laptop has difficulties to communicate with Mitsubishi PLCs in industrial environments with high noise levels where the desktop computer has no data errors at all using the same cable. Thus, even far beyond the minimum voltage levels, 2 volts extra can make a huge difference in communication quality.

Despite the high voltages present, it is not possible to destroy the serial port by short-circuiting. Only applying external voltages with high currents may eventually burn out the driver chips. Still then, the UART won’t be damaged in most cases.

Maximum cable lengths

Cable length is one of the most discussed items in RS232 world. The standard has a clear answer, the maximum cable length is 50 feet, or the cable length equal to a capacitance of 2500 pF. The latter rule is often forgotten. This means that using a cable with low capacitance allows you to span longer distances without going beyond the limitations of the standard. If for example UTP CAT-5 cable is used with a typical capacitance of 17 pF/ft, the maximum allowed cable length is 147 feet.

The cable length mentioned in the standard allows maximum communication speed to occur. If speed is reduced by a factor 2 or 4, the maximum length increases dramatically. Texas Instruments has done some practical experiments years ago at different baud rates to test the maximum allowed cable lengths. Keep in mind, that the RS232 standard was originally developed for 20 kbps. By halving the maximum communication speed, the allowed cable length increases a factor ten!

 

 

RS232 cable length according to Texas Instruments
Baud rate Maximum cable length (ft)
19200 50
9600 500
4800 1000
2400 3000

Ref: RS232 Specifications and standard - Lammert Bies


Re: FW: [RaspberryPi-4-HamRadio] Long serial cable issue

ve3smf
 

RS232 physical properties

The RS232 standard describes a communication method capable of communicating in different environments. This has had its impact on the maximum allowable voltages etc. on the pins. In the original definition, the technical possibilities of that time were taken into account. The maximum baud rate defined for example is 20 kbps. With current devices like the 16550A UART, maximum speeds of 1.5 Mbps are allowed.

Voltages

The signal level of the RS232 pins can have two states. A high bit, or mark state is identified by a negative voltage and a low bit or space state uses a positive value. This might be a bit confusing, because in normal circumstances, high logical values are defined by high voltages also. The voltage limits are shown below.

 

 

RS232 voltage values
Level Transmitter
capable (V)
Receiver
capable (V)
Space state (0) +5 … +15 +3 … +25
Mark state (1) -5 … -15 -3 … -25
Undefined -3 … +3

 

 

More information about the voltage levels of RS232 and other serial interfaces can be found in the interface comparison table.

The maximum voltage swing the computer can generate on its port can have influence on the maximum cable length and communication speed that is allowed. Also, if the voltage difference is small, data distortion will occur sooner. For example, my Toshiba laptop mark’s voltage is -9.3 V, compared to -11.5 V on my desktop computer. The laptop has difficulties to communicate with Mitsubishi PLCs in industrial environments with high noise levels where the desktop computer has no data errors at all using the same cable. Thus, even far beyond the minimum voltage levels, 2 volts extra can make a huge difference in communication quality.

Despite the high voltages present, it is not possible to destroy the serial port by short-circuiting. Only applying external voltages with high currents may eventually burn out the driver chips. Still then, the UART won’t be damaged in most cases.

Maximum cable lengths

Cable length is one of the most discussed items in RS232 world. The standard has a clear answer, the maximum cable length is 50 feet, or the cable length equal to a capacitance of 2500 pF. The latter rule is often forgotten. This means that using a cable with low capacitance allows you to span longer distances without going beyond the limitations of the standard. If for example UTP CAT-5 cable is used with a typical capacitance of 17 pF/ft, the maximum allowed cable length is 147 feet.

The cable length mentioned in the standard allows maximum communication speed to occur. If speed is reduced by a factor 2 or 4, the maximum length increases dramatically. Texas Instruments has done some practical experiments years ago at different baud rates to test the maximum allowed cable lengths. Keep in mind, that the RS232 standard was originally developed for 20 kbps. By halving the maximum communication speed, the allowed cable length increases a factor ten!

 

 

RS232 cable length according to Texas Instruments
Baud rate Maximum cable length (ft)
19200 50
9600 500
4800 1000
2400 3000

Ref: RS232 Specifications and standard - Lammert Bies


Sparkfun now has Pi 400 in stock

Dave R
 

I have no connection to Sparkfun. (I found my Pi 400 kit at CanaKits.) 73


Re: Best log SW on Pi for WFD?

Heath Petty
 

I was planning on using: https://github.com/scotthibbs/FDLog_Enhanced  It has support for winter field day. 

-Heath

On Sat, Jan 23, 2021 at 7:35 PM Troy - K4JDA <troy.davis@...> wrote:
What’s the best Pi logging SW to use for Winter Field Day? Thinking about doing Pi only ...


Re: Best log SW on Pi for WFD?

Glen - G0SBN
 

Troy

Do a quick search on YouTube for "Fldigi field day" there's a couple of videos which may help if needed.

73 Glen


Re: Best log SW on Pi for WFD?

Glen - G0SBN
 

Hi Troy

I'm not saying it's the best, but Fldigi may be worth checking out if using data modes. I noticed in the Fldigi configuration there's options to setup a multi-op Field Day logging Server/Client.

73 Glen


Re: Best log SW on Pi for WFD?

Lee - WB4QOJ
 

Watching for answers .

Lee WB4QOJ


On Sat, Jan 23, 2021, 10:35 PM Troy - K4JDA <troy.davis@...> wrote:
What’s the best Pi logging SW to use for Winter Field Day? Thinking about doing Pi only ...


Best log SW on Pi for WFD?

Troy - K4JDA
 

What’s the best Pi logging SW to use for Winter Field Day? Thinking about doing Pi only ...


Re: lost audio out in wsjt-x

David Ranch
 


It's TERRIBLE advice to other users to "never ever" patch your computers.  If they are connected to a network that can reach the Internet, you're putting your system at risk as there are just too many ways that computers can be compromised these days (web browsing, looking at PDF files, etc).  The primary way to keep your risks low is to keep them patched and reboot when required.  A pain?  Absolutely.  Necessary evil?  Absolutely!

The back up of SD cards is a good idea.  This is also very important as SD cards just aren't intended for any heavy duty write operations.  If they are used this way, it's only a matter of time before your SD card fails.  Current image backups will make moving to a new SD card very simple and painless.

--David
KI6ZHD


On 01/22/2021 08:57 PM, bbillp wrote:
Once your Pi is working never ever do an UPDATE, it makes no sense unless there is an absolute requirement by the developer of the application software.   Create a backup image of your SD card once you are satisfied with operation.







Re: lost audio out in wsjt-x

N5XMT
 

Really?  As the linux developers find flaws in their code they put out newer versions.
There are thousands of files and hundreds of packages and just a correction to one of the files in a package and it downloads the whole package.
No need to be a smart ass.

On Jan 23, 2021, at 09:16, bbillp <b.bill.p@...> wrote:
Then Name the security updates. 






Re: lost audio out in wsjt-x

Dave R
 

I'm pretty sure the list will tell you. 73


On Sat, Jan 23, 2021, 09:16 bbillp <b.bill.p@...> wrote:
Then Name the security updates.






Re: lost audio out in wsjt-x

bbillp
 

Then Name the security updates.


Re: lost audio out in wsjt-x

N5XMT
 

Updates fix security issues that are discovered.  Bad advice to never do updates

On Jan 22, 2021, at 20:57, bbillp <b.bill.p@...> wrote:
Once your Pi is working never ever do an UPDATE, it makes no sense unless there is an absolute requirement by the developer of the application software.   Create a backup image of your SD card once you are satisfied with operation.






Re: lost audio out in wsjt-x

bbillp
 

Once your Pi is working never ever do an UPDATE, it makes no sense unless there is an absolute requirement by the developer of the application software. Create a backup image of your SD card once you are satisfied with operation.


Re: lost audio out in wsjt-x

Jay Lijoi
 

Good day,

I bit the bullet and started with a new image on my Raspberry PI and loaded all new software (a lot of time). Still don't know why or where the problem was, but I'm up and running.


Thank you for your help,
Jay wb211j


Re: USB lock

David Ranch
 


If you're needs are simpler and your devices identify themselves uniquely (not always a for-sure thing), you can use the "by-id" naming system already available on your system.  For example on my machine:

$ ls -la /dev/serial/by-id/
total 0
drwxr-xr-x 2 root root 200 Jan 20 14:16 .
drwxr-xr-x 4 root root  80 Jan 16 20:58 ..
lrwxrwxrwx 1 root root  13 Jan 16 20:58 usb-FTDI_Navigator__CAT___2nd_PTT__00000000-if00-port0 -> ../../ttyUSB0
lrwxrwxrwx 1 root root  13 Jan 16 20:58 usb-FTDI_Navigator__CAT___2nd_PTT__00000000-if01-port0 -> ../../ttyUSB1
lrwxrwxrwx 1 root root  13 Jan 16 20:58 usb-FTDI_Navigator__RS232___Config__00000002-if00-port0 -> ../../ttyUSB4
lrwxrwxrwx 1 root root  13 Jan 16 20:58 usb-FTDI_Navigator__RS232___Config__00000002-if01-port0 -> ../../ttyUSB5
lrwxrwxrwx 1 root root  13 Jan 16 20:58 usb-FTDI_Navigator__WKey___FSK__00000001-if00-port0 -> ../../ttyUSB2
lrwxrwxrwx 1 root root  13 Jan 16 20:58 usb-FTDI_Navigator__WKey___FSK__00000001-if01-port0 -> ../../ttyUSB3
lrwxrwxrwx 1 root root  13 Jan 20 14:16 usb-FTDI_usb_serial_converter_FTCAWZIA-if00-port0 -> ../../ttyUSB6
lrwxrwxrwx 1 root root  13 Jan 20 14:16 usb-Prolific_Technology_Inc._USB-Serial_Controller-if00-port0 -> ../../ttyUSB7


In an application, I would just configure my serial port as /dev/seria/by-id/usb-FTDI_usb_serial_converter_FTCAWZIA-if00-port0 and I'm done!

--David
KI6ZHD



On 01/19/2021 09:02 AM, John D Hays - K7VE wrote:
You can create a udev rule which will make sure the IC-7300 always has a /dev file name that is consistent.  Udev rules files go in /etc/udev/rules.d

See example file content at: 
https://gist.github.com/peteonrails/fa99d57b58315a57631956c7e68f4d00

This should create a file /dev/ic7300 when you plug in your radio.  You can then use this instead of /dev/ttyUSBx and will be consistent between invocations.  /dev/ic7300 will be a dynamically assigned link to whichever /dev/ttyUSBx is assigned to the radio.



On Tue, Jan 19, 2021 at 8:21 AM Jay Lijoi <lijoi@...> wrote:
Good day,

I usually have to go to settings and pick my serial port, usually USB0 in my case, every time I start WSJT-X. Is there a way to have it connect to my ic-7300 consistently, or I'd this just the nature of Linux dynamic allocation of serial devices?

Jay
WB2QQJ
_,_


--
John D. Hays
Kingston, WA
K7VE

 



Re: lost audio out in wsjt-x

N5XMT
 

Best bet would be to open an issue on the wsjt-x github. It's obviously an issue with the sw and not a pi issue

On Jan 19, 2021, at 14:50, Jay Lijoi <lijoi@...> wrote:
Good day,

Here is what happens:

  • Using version wsjt-x 2.2.2 I lost audio out to my ic-7300
  • switched to 2.2.3 and all worked
  • 2.2.3 taken down by developer
  • reinstalled fresh 2.2.2 and no audio out
Equipment:
IC-7300
Raspberry PI 4 computer


I don't understand the difference between the two versions, but something is definitely different. As of now I can't operate wsjt-x.

Jay
WB2QQJ

#wsjt-x
#audio


lost audio out in wsjt-x

Jay Lijoi
 

Good day,

Here is what happens:

  • Using version wsjt-x 2.2.2 I lost audio out to my ic-7300
  • switched to 2.2.3 and all worked
  • 2.2.3 taken down by developer
  • reinstalled fresh 2.2.2 and no audio out
Equipment:
IC-7300
Raspberry PI 4 computer


I don't understand the difference between the two versions, but something is definitely different. As of now I can't operate wsjt-x.

Jay
WB2QQJ

#wsjt-x
#audio


Re: USB lock

David Birnbaum
 

I have done this for both my radio, Winkeyer and NanoVNA.  Works perfectly.  Independent of which USB port the radio is plugged into/

dave
k2lyv

Virus-free. www.avast.com


On Tue, Jan 19, 2021 at 12:02 PM John D Hays - K7VE <john@...> wrote:
You can create a udev rule which will make sure the IC-7300 always has a /dev file name that is consistent.  Udev rules files go in /etc/udev/rules.d

See example file content at: 
https://gist.github.com/peteonrails/fa99d57b58315a57631956c7e68f4d00

This should create a file /dev/ic7300 when you plug in your radio.  You can then use this instead of /dev/ttyUSBx and will be consistent between invocations.  /dev/ic7300 will be a dynamically assigned link to whichever /dev/ttyUSBx is assigned to the radio.



On Tue, Jan 19, 2021 at 8:21 AM Jay Lijoi <lijoi@...> wrote:
Good day,

I usually have to go to settings and pick my serial port, usually USB0 in my case, every time I start WSJT-X. Is there a way to have it connect to my ic-7300 consistently, or I'd this just the nature of Linux dynamic allocation of serial devices?

Jay
WB2QQJ
_,_



--
John D. Hays
Kingston, WA
K7VE

 


Re: USB lock

 

You can create a udev rule which will make sure the IC-7300 always has a /dev file name that is consistent.  Udev rules files go in /etc/udev/rules.d

See example file content at: 
https://gist.github.com/peteonrails/fa99d57b58315a57631956c7e68f4d00

This should create a file /dev/ic7300 when you plug in your radio.  You can then use this instead of /dev/ttyUSBx and will be consistent between invocations.  /dev/ic7300 will be a dynamically assigned link to whichever /dev/ttyUSBx is assigned to the radio.



On Tue, Jan 19, 2021 at 8:21 AM Jay Lijoi <lijoi@...> wrote:
Good day,

I usually have to go to settings and pick my serial port, usually USB0 in my case, every time I start WSJT-X. Is there a way to have it connect to my ic-7300 consistently, or I'd this just the nature of Linux dynamic allocation of serial devices?

Jay
WB2QQJ
_,_



--
John D. Hays
Kingston, WA
K7VE

 

341 - 360 of 13210