Serial <> USB interface?

[colmin]

Hi,

I need to connect a microprocessor based legacy product via its standard serial EIA-RS232 interface, or directly from its CPU UART port pins to a Palm OS PDA USB port.

As the microprocessor does not support PC software and hence software drivers, the interface must provide this function in hardware. (or provide driver code for 8051 MCU)

Please can you advise where I can obtain such a cable, device or integrated circuit solution?

Regards

Colin

[Jim Cooke]

Colin,

The only serial to USB adaptors I know of require Windows and will need drivers if your aren't using WinXP. I assume you must be using DOS or some proprietary OS from something like a SCADA system. I don't know of any serial adaptor that uses a hardware interface although there may be something that can be custom developed. If you're only using the Palm to monitor the PC, why not pick up a cheap Palm IIIxe that already has the requisite serial port? I suspect this will be both the cheapest and easiest way to go.

[colmin]

Dear Jim,

Thanks but you'e telling me what I already know.

My requirement is for a connection to an embedded microprocessor which doesn't run Windows. A number of companies manufacture such a device that incorporates the smarts but they are big, bulky and expensive.

Your suggestion is a solution but I already use the Clie TJ-25 and Belkin F8Y1102 Combo "Y" USB/Serial cable. Both of these were stock items a year ago but have now been pulled. Since the application is for an ongoing product I can't offer a hard to obtain or second hand solution and since most PDA's now and will support USB I prefer to take this tack.

Several IC manufacturers make "Bridge" chips that rely on being connected to a PC but the best solution would be one that just does full duplex EIA to USB conversion and I know that's not impossible but not where to purchase it.

Cheers

Colin

[Jim Cooke]

And you're telling me what I already know. :)

There's a difference between rigging up a Palm to monitor one PC compared to supporting an ongoing application that's being sold to customers. It helps if you let me know that information up front.

Belkin has discontinued the Y cable for both the Sony and Palm but there are still some available online. F8P310 is the Belkin stock number for the Palm version of the Y cable. Belkin also makes a direct Universal connector to serial cable. The part number is CL-603.

The issue is that Palm no longer uses the universal connector for its latest units but a mini USB. I don't know if you're selling this product with the cable and not the Palm or what but a customer is going to face ongoing problems trying to connect to serial port as time moves along. I know it's difficult to change the program if all the data is coming over the serial port but you're going to have to bite the bullet and do so or provide increasingly obsolete equipment to your customers.