B&K Precision bench multimeters, good?

Yes, we need a _simple_ interface, not this USB monstrosity. RS232 comes close, although still not close enough. Making things simple is hard.

Jeroen Belleman

firmaware upgrade?

Because it's *CHEAP* and *UBIQUITOUS*. That's a pretty damned good reason.

What a moron.

Sure. I'd prefer the hardware look more like RS422 but you can't make the data format much more simple (other than there are so many standards to choose from;-).

The USB to RS232 chips are dirt cheap, and could be added to the meter. You could still bit bang the instrument from a terminal program.

Yeah. Just add another layer. Diametrically opposed to what I'd really like to see. But cheap it is, I grant you that.

Jeroen Belleman

Most USB and network equipment comes with fw upgrade capability. No bit-banging required.

Nothing is as dirt cheap as a piece of wire.

If a usb instrument enumerates as an RS232 port, it looks like a COM port to the OS. If it uses or emulates the FTDI chips, you usually won't even need a driver.

The USB-to-RS232 dongles usually work without a lot of hassle.

I don't think the USB-to-parallel parts are useful for bit banging. That's sad.

We have a FLIR thermal viewer that's USB but acts like a network device. It's horrible. It only works on the same USB port as you used when you installed the software.

The USB to TTL serial converter is close in costs to the ttl to RS-232 chip & parts. If your computer has no RS-232 port, you'll need a more expensive converter.

If the only thing you're interfacing to is a laptop, sure, USB is probably the way to go, unfortunately.

data

If it is a portable test instument, it's likely you'll have to use a laptop.

data

Maybe.

- RS-232 devices dosn't require system driver which could be missing when you're getting a new version of ms-windows, for example.

- RS-232 ports are so easy to connect to cheap microcontrolers.

- (trues hardware) RS-232 ports are so fiables. I've heard this some time ago : "if I wanted my devices to randomly disappear from the bus, i'd go use USB." (a thing i've already saw, and not only when i'm using some high-voltage supplies).

- You usually don't need root privileges to use a new rs232 device. With USB, you need it to install the driver.

- I never got a BSOD/kernel panic with a rs232 port. so many with usb thingies :)

Cons:

- You need to know what is the number of the rs232 port you want to use... So, total newbies can't use rs232. Especially when the host computer got a half dozen of unlabeled rs232 ports to connect many devices in the same time. Usually to find out, I open the same amount of Putty consoles to each serial ports and I type things while shorting pins 2 and 3 to a port with a little screwdriver to identify them. If it's echoing, it's the good port, and tested-working !

cLx you're getting a new version of ms-windows, for example.

The better serial to USB dongles use the serial port CDC so don't need any drivers.

Wrong again. Newer versions of Linux, OSX and Windows know all populair serial to USB devices. Plug & play.

:)

Get a better motherboard. The problem is usually a crappy USB host chip with crappy drivers.

On 2012-12-21, cLx you're getting a new version of ms-windows, for example.

this problem seems to be unique to MS-Windows.

say what?

One problem with serial ports (of both types) is third-party software locking them, On windows it's quite hard to find the process responsible.

mainly a windows problem.

I had some ports with a clock that was 10 times higher than normal, they passed the loopback test but couldn't communicate with the hardware until I figured that out,

Windows 7 has problem with the most popular type * "Counterfeit PL2303" Microsoft is reliant on drivers supplied by Prolific. linux etc has drivers baed on the PL2303 datasheet and these don't reject the clone chips. As a result there's a lot of hardware that doesn't work

These fake pl2303's seem to function adequately for driving rs232 comms, but the handshaking lines are too sluggish for bitbang.

I have not tested a genuine PL2303 to see if it handles this better.

:)

I managed to crash an early version of linux while strobing the inbound handshaking lines at a high rate, perhaps a stack overflow, or some sort of race condition in the "8250" driver?

USB is not only for USB to RS232 converters, you know ? Plus, they need drivers too, just they're generally already packed with the system install, but not always. On my windows laptop computer, I had to install the drivers (ftdi and prolific). Not on my linux boxes, that's true.

Where I'm working, we're not into the "populars" stuff, trust me.

thingies :)

USB-Russian-Roulette. ;)

or data

make

program.

Just bought a new laptop. A nice one. No parallel port, no TIA-232 port. USB2 and USB3, HDMI, WiFi, 1000-BASETX wired NIC, other goodies. The trend is clear, if you need TIA-232 (more likely TIA-423) USB adapters are the transitional answer. Industrial electronics (including SCADA) is finally going 10/100 BASE-T.

?-)