On 5/19/2025 9:29 AM, Michael Mandell via groups.io wrote:
<snip>

With a normal USB cable, serial transmissions are broken into
packets, so your radio will transmit D-Rats serial data in chunks. It
goes on and off in xmit to get the whole thing out.

It should not be doing that unless somethings is wrong. Yes the USB breaks up the serial data into chunks, but it can fit an entire d-rats packet into one chunk.

What USB is doing is delaying sending any characters until its buffer reaches fixed mount, or there is a very small time that no additional characters are added to the buffer.

The radio has an XON/XOFF handshaking to slow D-Rats down to the speed that the radio can accept.

With the RT Systems cable and the radio data port, serial is a
continuous stream and it goes out in one shot.

I called Icom on this and got a support guy in Texas who explained
the whole thing to me. Both work, but the orange data cable (Icom
has one, too, but it costs way more) is a better solution.

I don't think you fully understand how that works.

D-rats transfers data to and from a USB serial port at a rate of about 30 Megabytes per second. In addition that transfer from the USB serial is done with what is known as a DMA transfer. Which means that it does hardly stresses your CPU utilization at all.

That means only one interrupt per transfer. Interrupts are costly for a PC to process, because it has to save context, process the interrupt and then restore it. The computer does this every time you do I/O except for screen writes. Most devices on your computer use DMA transfer.

On a "standard" older PC that still has a serial port, it has a very small buffer and must interrupt the PC once it has either filled the buffer or emptied the buffer. So at best, it is processing one of those interrupts on every two characters transferred. D-Rats sends/receives around 200 bytes per transfer, so that is at least 100 interrupts per transfer.

Now most people don't load up their PCs to the point where that makes a difference.

But your PC can handle at least 20 times the number of USB ports running flat out with data than the maximum number of "standard" serial ports it can support. And it was hard to even add enough "standard" serial ports to cause a strain on the last models of PCs that had them available.

Yes, USB delivers the first character in a bunch of characters slightly slower than the serial port. If you get a good enough analyzer you can see that easily. However your computer is working much harder to deliver that data on using the older serial port.

So use what ever cable you want to use.

73,
-John

On 5/11/2025 10:35 AM, John E. Malmberg via groups.io wrote:

On 5/9/2025 6:08 AM, Facundo Fernandez-KK4ODA via groups.io wrote:

Hello, I have seen posts of hams using D-RATS with FLDIGI modes
instead of DSTAR. I have tried this with various degrees of success.
It occurred to me that it may be possible to run DRATS with VARA as a
modem.

Finally found this document:

Actually the relevant document is:


73,
John
wb8tyw

On 5/9/2025 6:08 AM, Facundo Fernandez-KK4ODA via groups.io wrote:

Hello, I have seen posts of hams using D-RATS with FLDIGI modes
instead of DSTAR. I have tried this with various degrees of success.
It occurred to me that it may be possible to run DRATS with VARA as a
modem.

Finally found this document:

However, I tried this using the default command port of 8300 with
no success. I know this is a long shot, but has anybody tested this
configuration succesfully?

Obviously I have no experience except from looking at the source code, but D-Rats generally does not send commands to TNCs and other Packet type modems. It assumes that they are already in either the AX25 or the KISS mode and only connects to them over what is presented to D-Rats as a serial device.

For VARA the above documentation says to use port 8100 for KISS mode.
As far as a modem is concerned KISS mode can also handle AX25 packets because in KISS mode just a raw 8 bit stream is sent over the radio.

This should work for AWGPE, as D-Rats seems to assume that the connection can handle AX25 frames, and parses the connection commands from the AX25 frames.

So far I have not found the username and password fields for the AGWPE connector used anywhere.

73,
-John

On 5/9/2025 10:01 AM, David Ranch via groups.io wrote:

I would think that D-RATS could be enhanced to work with D-RATS but it shouldn't be done via the old school KISS interface.? It would need to be done via the VARA native interface.

I have done a bunch of searching this morning and can not find anything that tells me anything about the VARA native interface or the KISS interface.

D-Rats implementation of Winlink seems to be limited to some message passing, not for chat.

D-Rats has basically these major modes of communication.

Repeater, after login, it just sends/receives its DDR2 Yencoded packets over a network connection.

Serial port: It just sends and receives its DDR2 Yencoded packets over the serial link and any radio modem that can pass through serial data will work.

AX25 mode: It sends/receives AX25 packets via the serial port or the AGWPE socket. Inside the packets is a DDR2 Yencoded packet.

KISS Mode: Looks like it just sends and receives DDR2 Yencoded packets through the serial port. Not sure if it can do that with the AGWPE interface.

Yencoding is needed for D-Star radios because the serial port is also used as a remote control for the radio and Yencoding filters out binary that could be interpreted by the radio.

If only sending data over a serial or network link is needed, the hardest part of modifying D-Rats is the way the current configure GUI is implemented and the glade tool that should allow customizing it easily is refusing to cooperate.

73,
-John

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I would think that D-RATS could be enhanced to work with D-RATS but it shouldn't be done via the old school KISS interface.? It would need to be done via the VARA native interface.?? If someone is looking for D-RATS like functionality but for VARA, check out VARAC:

??


It implements a lot of similar concepts in D-RATS, FSQ, etc. The interface is a bit complex but you get used to it.? It and both the VARA-FM or VARA-HF modem programs run fine under Wine for Linux and Mac users.? The tool automates all that installation which makes it a snap.


There is also vARIM tool as well which is very powerful but more complex:

??



--David
KI6ZHD

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DRATS uses several types of net linkage, including internet and RF. It does not have to speak DSTAR data. Best approach is to start with the most recent version 3.x and play with it while reading through some of the old documentation (in the files section) to get the basic set up. Ask questions here.

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John,?

Hello all,

In doing some research on improving the D-Rats I have discovered a hardware error which seems to be in a number of TNCs.

I have found this documented (not as the hardware errata that it is) in two different PAC-COMM TNC manuals and in an MFJ TNC manual.

If you are generally using only the quick wiring of RX data, TX data and signal common on the packet modems then you should be OK.

If you are using the "non-standard" wiring documented in the TNC manuals they you also should be OK.

But who bothers to read the manuals in detail? And when you see a 9 pin or 23 pin serial port, you may just plug in a standard wired cable like common ribbon base cables.

If you are using a standard full wired cable you could be in danger of burning out the serial port on your computer or causing other damage to the or USB serial adapter.

Someone made a big mistake about those signals and it looks like everyone copied them instead of correcting it.


The TNCs are expecting the custom non-standard cable where the CTS signal from the computer is wired both to TNC CTS signal and the TNC DTR signal. And that the cables do not have anything connected to pins 9 and 10 of a 23 pin connector.

This is not the way that off the shelf standard full signal cables are wired, either have all signals wired straight through or the common MODEM subset of 9 wires wired straight though.


Worse is that TNCs may be incorrectly shorting CTS and DTR signals together inside the TNC, as documented in the PAC-COMM TINY TNC-2 which stated that it is based on the TAPR reference model. That is one of the things that can burn out your computer!

And also that if the cable has a 23 pin connector, that pins 9 and 10 are not connected, since the TNC may be unexpectedly providing power signals to those pins, which are defined in the specification as reserved. This should be ignored, but if the computer is doing something non-standard on those pins, that could cause a problem.


Why this is a problem, is what the standard computer interface is supposed to be doing:

The DTR pin when you are not using the serial port should be setting the DTR and the CTS signal to a value of about +3 to +15 volts.

When a program is running using the serial port, the DTR signal is typically set to about -3 to -15 volts.

The CTS signal when hardware handshaking is disabled should also be set to -3 to 15 volts, but may be left at +3 to +15 volts, which when using a standard wired cable is a short circuit of up to 30 volts.

When hardware handshaking is enabled, the DTR signal stay at the -3 to -15 volts, and the CTS signal can periodically alternate between the positive range and negative range, which is an intermittent short circuit of up to 30 volts.

It is on the expensive computer side where the damage can occur.

There are about 2 to 4 different documented ways (3 wire and 9 wire) that 9 and 23 pin connector serial connectors should be wired that will work 99.9% of all devices.

There are seems to a very small number of devices that need special wiring because the hardware designers did not implement the specification correctly. So far I have only encountered one commercial printer, and some TNC modems that require a variant from a standard cable wiring.

And also because people do not bother learning and following the specification there are hundreds of wiring diagrams on the Internet for 9 and 23 pin serial port connectors, with most of the 3 wire implementations missing jumpers for DSR/DTR and RTS/CTS signals on the 9 or 23 pin connector side.

And now I need to make and keep track of special cables for my older TNCs, so that I can test them in AX25 and KISS modes.

73,
-John
wb8tyw

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