Modified Serial Interface for USB-Serial Adapters possible?

[weini]

I just build myself a serial interface and wanted to use it with a USB-Serial adapter (Prolific Chipset 2303).
Too bad, I had no luck!

The interface works well on a "real" serial port, but refuses to work on the USB-Serial adapter. The error message says that it has a power problem.

My guess is that the USB-serial adapter does not provide enough power to create the necessary signal levels.

I see two possible ways out of this:
a) reduce some resistor values to have more power available
b) modify the circuit to get the power from an external 5-6V supply

Did anybody already do this? Are there plans for a modified serial interface?

[Evan_s]

is this the jp1 serial or the jp1.x serial cable?

if it is the jp1 serial cable it won't work. Build the usb version.

If it's the jp1.x serial cable they usually work with usb-serial adapters with no problems.

[binky123]

A JP1 Serial Interface will NOT work with a USB-Serial Adapter as the software needs direct access to the serial port pins.

There is a JP1 design that uses a DelCom USB chip and the DelCom driver for direct access to the USB chip pins.

Someone was able to modify their USB-TTL Serial adapter with PL2303 chip inside for use with a JP1.3 Remote in this thread.

There have been some discussions on using a PL2303 or FT232RL or a newer DelCom chip to handle both JP1 and JP1.x remotes. Any USB chip that is used will involve using their own driver to get direct access to the chip pins for JP1 access. JP1.x access should be fairly straightforward with any USB chip.

[weini]

Too bad, it is a IP1 cable!

So I will have to look for buying or building an USB one...

Thanks for you feedback!

[Capn Trips]

I guess "Choose the right JP1/JP1.x interface cable - Read this first" is a misleadingly-titled sticky post.