RS232 com port not recognized

I just for the first time attempted to connect an 08M on a board using standard rs232, but picaxe says the comm port is not connected or something like that. I said to measure voltages at serial in. I get 0V no matter what. Any suggestions?

Also, can you use any USB to serial setup or do you have to use the AXE027?

I would really like to get this going but I can't seem to get past the connection hurdle. Any help would be appreciated.

John M

Do you see the port in the device manager?

You can't use ANY USB converter. It must be one which is capable of sending the 'break' signal. I can't remember which chip set that is so to play safe, get the AXE027.
Make sure you have configured for the correct com port in the options settings. There's no point doing any voltage tests until you get the comms working. Maybe somebody else can help with tips on the PC side of things.

What cable are you using; a Rev-Ed one or something home built ? Likewise is the board you are connecting to a pre-assembled board or something you created or built yourself ?

If it's a home made cable getting the wires crossed-over can be a problem, and similar if you've used a PC serial to 3.5mm jack cable you happened to have to hand, some of those for camera's and PDA's are wired differently to how they need to be for a PICAXE board.

USB seems OK with FT232 or Prolific chips. Have 2 different profilic chip based cables/converters and both work fine.

These chips were confirmed by Technical as OK some time back.

hippy said:

What cable are you using; a Rev-Ed one or something home built ? Likewise is the board you are connecting to a pre-assembled board or something you created or built yourself ?

If it's a home made cable getting the wires crossed-over can be a problem, and similar if you've used a PC serial to 3.5mm jack cable you happened to have to hand, some of those for camera's and PDA's are wired differently to how they need to be for a PICAXE board.

Click to expand...

Im using a store bought (Radio Shack) cable. The board is a pre-assembled one I got from ebay P Anderson. Also how do I verify that my comports are working? I show Com2 and com4 and last night showed com1 as all working according to device manager. Today com1 is grayed out.

BeanieBots said:

You can't use ANY USB converter. It must be one which is capable of sending the 'break' signal. I can't remember which chip set that is so to play safe, get the AXE027.
Make sure you have configured for the correct com port in the options settings. There's no point doing any voltage tests until you get the comms working. Maybe somebody else can help with tips on the PC side of things.

Click to expand...

But how do you know which com port?

Remove the usb cable. Take a look at the device manager
Now insert the cable, take a look at the device manager, it should show a new port. That's the port for your usb cable.

What OS are you using - Vista or XP?

I'm not using a USB cable (yet). I'm using a computer that has both serial RS232 and usbs. I am trying to use the ordinary old com port. Device manager shows three available com ports but there is only one DB9 connector on the back. I only mentioned USB because I thought I may need to try USB on my other computer that has only USB ports.

Hi Johndx
I think you answered your question a couple of post ago the serial cable to the prototype board is it wired as per the Picaxe manuals see page 21 of section 1

What does the Programming Editor indicate under View/Options/Serial Port(tab)?
Have you tried changing the default and having another go?

Sooner or later with RS232 you need to roll up your sleeves and get your hands dirty.

The computer thinks you have 3 com ports, but nothing comes out the port? Well, the motherboard might have three 10pin headers on the board, but only one might actually be connected to the D9. Or worse, none. So first step, pull off the case and just check it is actually connected onto the motherboard.

Most likely you have two RS232 connections, COM1 and COM2. COM4 is usually a psuedo port for talking to modem cards.

Next, you should have a male D9 on the back of the PC. If you can, grab a multimeter, and very carefully put the black lead on pin 5 and the red lead on pin 3. You may need a torch to read the numbers. You might even want to make a female D9 plug with wires coming off it so there is less risk of shorts. (Though RS232 can handle shorts)

Now fire up hyperterminal - it usually is hiding in windows/accessories. In the settings:
First screen=name the connection. Call it Test and choose an icon.
Second screen. Set the com port. My computer defaults to COM2 on the setup screen, and it needs to be changed to COM1. Change to COM1.
Third screen. Baud rates etc. Set the bits per second to 110. 8 Data bits. Parity to None. Stop bits to 1. And Flow control to None. You will probably only need to change bits per second and Flow Control.

110 baud is the slowest - choose the slowest so you can see the data. With the multimeter on those same pins, try typing something. You should see the volts go +ve as the data goes out. Nothing will appear on the screen - don't worry about that.

If no voltage change, try with com2 and com3 etc.

Then if that works, try a loopback test. Grab a D9 female plug, join pins 2 and 3 together. Plug it in the back. Now when you type something in hyperterminal, the character should appear on the screen.

If you get that far, it may well be quicker to solder up your own download cable. You only need a stereo plug, a D9 female plug, and 3 wires.

'Simple' RS232, ie the one I like and Rev Ed uses, only has 3 pins. Pin 5 is ground. Pin 3 is data coming out of the computer and this goes to the Rx pin of the picaxe via a resistor. And pin 2, which is data from the picaxe back to the PC

@Johndx. re. your post #6,

is the board shown on this page?

http://www.phanderson.com/picaxe/index.html

Hippy mentioned “crossed wires” in post #4.

Is the RadioShack cable “straight” or “crossover”?

e.

centrex said:

Hi Johndx
I think you answered your question a couple of post ago the serial cable to the prototype board is it wired as per the Picaxe manuals see page 21 of section 1

Click to expand...

I'll check out that reference. Could it that I need a null connection?

John.

This diagram is taken from Manual 1, page 31.
(Access from "PICAXE Manual" above)

It may help you to test your cable/board connections.

e

Good post eclectic. I have built several of those. You don't need a null modem cable or anything complex. Just that female D9 and the 3 wires. Solder a few metres of wire, and then you can bring out the wires to the front of the computer and it makes testing a lot easier. Just for starters, is there -9V between the pin 3 wire and the pin 5 wire?

programming

windows 7 doesn't carry hyperterminal, it is that possible that you can programm a picaxe pic only with the picaxe editor?

vcabanillas said:

windows 7 doesn't carry hyperterminal, it is that possible that you can programm a picaxe pic only with the picaxe editor?

Click to expand...

The free Programming Editor the only way to program a PICAXE. Very few PICAXE users would use hyperterminal when communicating with (an already programmed) PICAXE.