Null-Modem/SerialPort on Amiga500 (build in 1988) doesn't work

[anmabagima]

Hi Amiga-Experts,

after many years i started my Amiga500 again and want to transfer some files via Nullmodem to my PC (WinXP). I bought a standard 7-wires null-modem-cable(25 to 9 pin's). I checked out the wiring (like shown on the AmigaExplorer pages, but it didn' work.
I tried a terminal programm on both side Amiga:NComm and at the PC a HyperTerminal. If i pressed some keys on the PC, the chars are displayed on the Amiga-monitor, but if i pressed some key's on the Amiga - nothing happend. No XModem or ZModem-Filetransfer works.

I found a selfmade cable with 2 25 Piin-connectors, but only on one side are the wires fix to the plug. If i compare the wireconnection on that cable with grahpics in the web that differs in some details.

I can remember, that a few years ago i transferd files with that cable between my amiga and an old PC(386) with Win95 wich had a 25pin serial port.

Now my question: are there any differences in the specifications of the serial port of the old amiga500, what other problem could it be ?
Why is on the old selfmadewiring the pins 20 and 8 are bridged

Thanks a lot for your helping.

By André.

[Spidey]

Hello anmabagima,

Welcome to Amiga.Org :-)

Years ago I also transferred files from pc to my A1200 (I believe the A500 has the same serial port as the A1200?).

For this I had to reroute some wires in the serial cable.
I also used a small program DOS-based which had to be activated from the pc- and Amiga-side (it's at the tip of my tongue).

I'll look into it this evening....oh wait, Aminet's the key-word :-D

Twin Express
Here's the direct link to the archive on Aminet:

LINK

And the cable I'll check this evening :-)

Bye,

Spidey

[anmabagima]

Hello Spidey,

thanks - but if i need a special program on Amiga-Side wich i don't have on an amiga-disk: Whow do i transfer it ty my amiga, while the simple serial-connection is not running ?

I tried out the AExplorer. The Setup-Process from the PC-Side transfer a small file to the Amiga. There i have to type in the cli: Type SER: RAM:Setup. The transfer is very fast and i do not have to hit ctrl+c on Amigaside to end the transfer. If i tried to run RAM:Setup i get the error, that it is not an object module. Also i tried to call "type file.xyz >SER:" at the PC-Side and "type SER: to RAM:file.xyz" at Amigaside. The transfer semmed to be running but at end the file at Amiga side is only a part of the original pc-file e.g. 800 Byte of a 4K-File.

Thanks for your help.

[spirantho]

You should check that the settings are the same on each machine - you want
9600 baud (to be safe.. try higher afterwards)
8 bits
N (No) stop bits
1 Parity bit

RTS/CTS flow control should do...

[anmabagima]

Hello spirantho,

thanks.
 I tried out a view connection parameters on both sides but ever have the same settings on PC and Amiga.

no baud rate work, whether i use XON/XOFF or RTC/CTS-Handshake.
The bigest question to me is: Why are the characters i typed in the HyperTerm on PC-Side are displayed on Amiga screen (what is good) and the characters i typed in NComm on Amiga doesn't send to PC or cannot recieved from PC.

Is that an one-way-connection Are there any tools to simply check the Serialport of my amiga ? In many papers in the web is written, that amiga don't use standard serial-port. Could it be that such a early A500 has special serialport "configuration" and i need special wiring ? Other to all of that what i found in the web.

Thanks a lot for help or tips what i can do.

[vic20owner]

The bigest question to me is: Why are the characters i typed in the HyperTerm on PC-Side are displayed on Amiga screen (what is good) and the characters i typed in NComm on Amiga doesn't send to PC or cannot recieved from PC.

I can't remember why this happens, but I can tell you for sure that it's an issue with hyperterminal. I've been through this issue many many times, and it's always related to crappy windows hyperterm.  I first had this problem when I was using hyperterminal to connect to a small microcontroller board for development.  I eventually got it working after tons of tweaking the baudrate in both the control panel and hyperterminal. I also had to close and start hyper terminal a bunch of times before it would go online correctly.  The problem was exactly as you describe.

Make sure CTS/RTS, etc, is set correctly (off or on) in the control panel too.

Do you have all of the documentation to AExplorer? THe readme describes how to set up the serial ports (if I remember correctly).  I did this on several Amigas a years ago and it worked perfectly, but I think there was a slight difference if you has older roms... I can't remember. I'll check it out.

In short, verify that the null modem cable is wired correcly, and then keep messing with hyperterminal until you get it working

tom

[Acill]

Hmm do you have a modem or anything to test the port? You may have a bad CIA chip causing the port to be dead. This  has happened to me in the past.

[anmabagima]

@vic20owner:

Thanks. I tested the wiring of my null-modem-cable with 2 pieces of wire, a battery and a small lamp. I think it was correct - only the bridges on both ends are missing (on the 9Pin-side 1-6 and the 25Pin-side 6-8)

I will try some configurations from the control panel for the com-Port and the hyperterm-settings - hoping that it will help.

but I think there was a slight difference if you has older roms... I can't remember. I'll check it out.

... waiting for reply


@Acill:

sorry - i don't have a modem ore somthing like that. What's the CIA-Chip and where can i get it if it is realy damaged ?
How can i test if it was the chip ?

Thanks.

By André

[Spidey]

Hi anmabagima,

Searched for the cable yesterday, didn't find it (I'll search again this evening).

About the communication.

I just remember using Twin Express.
In the archive there are 2 programs, one to run on the Amiga and one on the pc.
Start both up with the same settings (for baud, etc.) and it should work both ways.
As I told you yesterday, I used this program a lot of times without any problems.

Bye,

Spidey

[anmabagima]

Hi Spidey,

i hope you will find it....

It is not a question about the tool to use for communication between Amiga and PC - i realy want to check out TwinExpress, but how to transfer it to my Amiga500. The a500 doesn't have an internet connection and no transfer from PC to Amiga over the serial-port is working. I tried it from the command-prompt on PC with "TYPE file >COM1:"
But the file on Amiga could not be executed and semmed not to be transfered completely.

[RiP]

I have the same problem with ADF Sender.
Hope someone can help

Hmm do you have a modem or anything to test the port? You may have a bad CIA chip causing the port to be dead. This  has happened to me in the past.

Are you sure? possible to check if the CIA is really dead or not?

[amyren]

Thats a really old thread you are breathing into life there:)
I wonder if anmabagina ever figured out the problem..

However I was thinking that using a serial analyzer tool on the windows pc might help. It shoul tell if if there is anything going on at the windows serial port.
I just googled it, so I havent tested this program. But I was thinking about something like this https://freeserialanalyzer.com

[Castellen]

Are you sure? possible to check if the CIA is really dead or not?

The CIA has nothing to do with the serial data, in every Amiga the serial UART is in Paula.  And this rarely has problems in this area.  One of the CIAs does the I/O on the serial control lines, but you don't need them for slower serial speeds or very short transfers.

A basic serial port test is as simple as:
1. Run your favourite terminal emulator (e.g. Term), set flow control to disabled, set any serial speed you like (e.g. 9600 baud), disable local echo

2. Perform a serial loopback by shorting/linking only pins 2 and 3 (TX and RX data) on the serial port - same pins for either the DB9 connector on the PC or DB25 on the Amiga

3. Type anything on the keyboard, you should see it echoed on the terminal window and echo will stop when you remove the loopback


If that doesn't work, you've either got the wrong port selected (e.g. serial.device unit 0 on the Amiga, COM1 on the PC), or you may have a hardware fault.  The common source of hardware problems would be the RS232 line drivers, the 1488 and 1489 in the Amiga.  Also check the +12V and -12V supplies are present as the line drivers require both of these supplies.


If the loopback test is OK, then with the same serial settings, connect your null modem cable between machines.  Serial speed will need to be the same on both machines (e.g. 9600 baud).  If you type on one, it should display on the other terminal.

If that doesn't work, there's probably a cable problem.  Ignoring flow control lines for now, you only need three wires for a basic null modem cable.

Code: [Select]


DB25 (Amiga)       DB9 (PC)
Pin 2 ------------- Pin 2
Pin 3 ------------- Pin 3
Pin 5 ------------- Pin 5


If using a cable with 2 x DB9 connectors or 2 x DB25 connectors, then swap pins 2 and 3 at one end only.

So if that all works OK, enable hardware flow control [RTS/CTS] on *both* terminals and repeat the typing test.  If that suddenly no longer works, there's possibly an issue with the hardware control lines (also driven by the Amiga 1488/1489).  You need to use flow control with longer serial transfers and faster serial speeds else you're likely to get buffer over-run errors.

Also check the looping and connections on the hardware control lines in the null modem cable.   I can't remember all the connection details, but there's plenty of websites with this information.

[RiP]

As I said, my Amiga 2000 can receive files from ADF Sender but can't send to PC.
It was working fine last month but the COM port got bad in a day.
So I believe it's a hardware problem but need to know how to fix it?
My Amiga 500 works fine with the same cable.