Should USB replace RS-232 ports?

I have had some bad experience with USB but now I look at my computer and my MP3 player, a USB hard drive, Logitech Web Cam, Mouse and Keyboard are connected to my computer using USB and I am NOT using RS-232 at all!

How does every feel about having a USB port on a PLC or more specifically a motion controller?

Bad points. 5 meters maximum cable lenght between hubs. No IP67 connectors yet.
Good points. Easy. No nodes or address, can connect to multiple PLCs or motion controllers.

RS-232 is going away. I hate proprietory communication links like MPI, SC09 cables and DH-485 boards.

My first choice is Ethernet but this is expensive. What should be a cheaper second choice?

Oh Yeah!! I would love to not have to carry around twenty different programming cables everywhere I go.

Probably Yes

Probably in time we will find USB on PLC'S but i belive that you will be using more the proprietory communication links like MPI, SC09 cables and DH- 485 boards.

It's my feeling that USB is best suited for relatively "simple" devices like mice and keyboards and such. Legacy systems are going to dictate standard RS-232 ports will be required on our PCs for a long, long time. I just bought a new laptop, and the choice was pretty much dictated by insisting on a built in serial port. In the future PCMIA cards may be required to get serial connections.

In terms of hooking up to a PLC, I'm pretty convinced that ethernet is going to be the method of choice. I don't really see any advantage of USB over ethernet, and most new PLCs have some kind of ethernet connectivity.

I am not sure the plc's will stay with the serial port stuff too much longer. The computer technology is moving away from serial devices to things like USB or Firewire (which makes more sense as a std then USB but VHS beat out Beta so who can say). The plc companies arent going to rush to make the changes though, they can stay with their proprietary and you have to buy their cards etc. With my laptop I have AB and Siemens PCMCIA card that will allow me to connect to just bout anything they got on the market, but it requires different cables for different series. Everything else is serial for plc's and similar.

Anyway I think in the future Ethernet will be the connection but there will still be some form of proprietary communication, the connection will just get simpler.

Now you are talking about other devices like motion controllers etc, hmmmm that could be unique. If I had to choose a BUS type as a standard I would prefer Firewire IEEE1394, its meant to uniform the bus types and provides the same services as existing IEEE std parallel bus. Seems that this should make it simpler (if need be to develop an adapter to connect to existing IEEE connections).

IEEE1394 ie Firewire would be my second choice and Ethernet my first.