PC pat cable

[maguire]

Hi All I hope this makes sense I have got a new PC and there is nowhere to connect my download cable to is there a RS232 to USB available I tried a PC forum but Jeez are those guys weird or what one guy rambled on about bit rates and digital unit reconfiguration blaa blaa al i need is a cable with a old bit one end and a new bit on the other
Dev

 

[russellellwood]

A friend had the same problem the other week, 3 options,
1 contact the company who make the pat tester and get a usb lead off them
2 buy a RS232 card and install it to the pc.
3 try and RS232 to usb cable

We tried a RS232 to usb cable but could not get it working so he got a RS232 card.

Russell

 

[OwainDIYer]

Yes, quite a few here

http://www.usbnow.co.uk/Cables-USB_to_RS232_Cables/c1_23/index.html

Unfortunately these type of units don't always fully support the full RS232 specification especially for downloading high speed data over long cables, also they can appear to software as COM3 or COM4 etc and some software may expect a physical RS232C port to be on COM1 or COM2

I would suggest buying from somewhere that accepts returns after you've tried it, in case it's not compatible.

Often you have to plug in the USB adapter, run driver software, before connecting anything to the RS232C end.

 

[Spark123]

What other sort of ports does the PC have?
I tried using a USB-serial convertor before but didn't have much success.

 

[TicklyT]

Or turn the problem on it's head - Does whatever you are downloading from support a USB interface in place of the RS232 interface you are using?

A few years ago, a lot of the comms kit I worked with started arriving from the suppliers with a USB interface fitted where the RS232 used to be.

 

[Monkeh]

The problem with USB to serial cables is voltage. Most devices will operate at 12V (or 10V, which is close enough). USB is 5V, this is all that is available to the adapter. A charge pump is required, and not all devices are fitted with them.

Jeez are those guys weird or what one guy rambled on about bit rates and digital unit reconfiguration blaa blaa

Just like you sparkies ramble on about Zs and R1+R2?

I'll post back with a link to a suitable adapter later, it can take some research to find one.

 

[maguire]

Thanks guys lots of ideas I will phone seaward maybe they offer a free cable yeah right although the idea of a change at the the tester end is woth investigating
Dev

 

[Monkeh]

Some searching indicates this should work fine.

 

[ban-all-sheds]

What other sort of ports does the PC have?

IEEE 1394 High Speed Serial Bus?

 

[slup]

Try and find a USB->Serial cable with the Prolific PL-2303 chipset.

Either eBay or Maplin Electronics should turn something suitable up.

The advantage of the PL-2303 chipset is that it uses the correct signal levels, and the drivers are well developed and supported on all versions of Windows, Mac and Linux

 

[Monkeh]

The advantage of the PL-2303 chipset is that it uses the correct signal levels

No, it does not. The PL-2303 does not contain a charge pump, and the signal level is either 3.3V or 5V (I don't have mine handy to check what it is presently, however it is most definitely not 12V.

 

[slup]

Sorry, you are quite right.

Our field engineers all carry cables with the PL-2303 and connect them to all manner of exotic and fussy equipment and we've never had a problem.

I erroneously assumed that was because they adhered to all the standards.

I wonder if some better, more expensive cables add something like a MAX232 to the back of the PL-2303?

 

[Monkeh]

The PL-2303 never claims to adhere to RS232, merely to provide an RS232-like interface.

I'd expect most to use the MAX233 or MAX233A, the MAX232 requires external components.

 

[maguire]

All I have is usb and a little D shaped female for a monitor, I think, and a ethernet socket. my last tosh had all sorts in a flap at the back but it seems the world has been converted to the almighty usb I thought they were, well universal! one size fits all seems like the revolution ain't over yet what I don't get is if serial is old hat why cant the new sheriff in town do the same job as the old bloke
Dev

 

[slup]

The PL-2303 never claims to adhere to RS232, merely to provide an RS232-like interface

Right, so most, if not all PL2303 cables have an additional device to provide the level change.

Ok, well I stand by part of my original point that the driver works well and is otherwise reliable - never had any software related issues with the PL2303.

It seems that it's down to the particular manufacturer of the cable as to whether all the lines are connected and at the right levels - so it's a lottery and picking a PL2303 based cable is no guarantee that it will work well electrically.