Bit rates and baud rates of industrial comms

I want to know the typical and max bit rates and baud rates that you've seen in the field for various field busses, comms busses, etc., and I'm more interested in the higher speed busses. Also I'm more interested in discussing baud rates (frequency) than bit rates, but I realize that baud is rarely spoken of with today's comms, so I'm more than happy to discuss bit rate and I will do the leg work to find the baud rate.

Sure, I can go look up the specs for modbus, profibus, devicenet, et. al. (and I already have), but that doesn't give me an accurate picture of what to expect in the field. For example, I know that the max bit rate for Profibus DP is 12Mbits/S, but how common is that? Have you ever seen a Profibus network operating at that speed? Do you see it every day? Or is it more common to see Profibus DP running closer to the minimum of 9.6KBits/S? I'm looking for the human experience factor to develop a general statistic that I can use to determine the bandwith of oscilloscope I need to enable to troubleshoot 95% of what I might encounter in the field.

This is related to my other current thread about using an oscilloscope to troubleshoot industrial comms busses. If you'd like to discuss whether an oscilloscope is necessary at all, scope bandwidth, or anything related to oscilloscopes, I would be happy to discuss it, but I would prefer to keep that discussion on the the oscilloscope thread. Let's try to keep this one about baud/bit rates please.

Thank you!

Sorry, but I see no benefit in this kind of 'narrow band' discussion that your other post does not cover.

Ethernet/IP, Modbus/TCP and most OPC run on Ethernet, so they're Ethernet speeds.

Their predecessors, Devicenet and Modbus RTU, run on RS-485, typically 38.8K or less. Most USB/485 converters max out at about 112K baud.

Profibus DP is engineered RS-485 and the network baud rate depends up on the network 'length'. Shorter lengths can run at greater speeds. Profi DP maxes out at 12Mb.

Foundation Fieldbus has a high speed version on Ethernet (fairly rare), and a low speed instrument bus version (like Profibus PA) that runs at about 40K baud.

Occasionally there's a CANbus question, but I don't know what speed CANbus runs at.

Ad Profibus DP:

A (qualified?) guess in my area, would be that 80% of the installations are 500-1500 kbit/s.

The rest is mostly 187,5 and 9,6 kbit/s running on totally off-spec wiring or radio lines.

I know a couple 12Mbit/s installations with few nodes and high demands on response time.

Kalle

I have setup profibus systems with 1.5, 3, 6 and 12Mbit/s and it can differ from system to system and depends on what Ttr time you require.

I have also experienced better Ttr with lower bitrates than higher bit rates too.

Oh dear - this would have to be the greatest can of worms of all time! Even the high speed busses like Ethernet IP and the like are so variable it is not funny!
Automatic data exchange allocation, reads, writes, storms, switches, crappy cable, QOS all affect the rate - and then you hook in with your programming software and it all goes to s**t! Slows down to heck when monitoring and/or online programming multiple PLCs.
The only comment I can make is 'how long is a piece of string'?