Profinet comm speed?

NetNathan

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First Profinet and covering all the bases..
Does anyone running a large Profinet install?
I have 9 locations on Profinet module (GE RX3i).
I have 4 ABB VFDs
3 have 46 Discrete I/O and 8 Analog IO (GE RSTI-EP)
2 have 16 Discrete I/O remote (Turck IO)

I am wondering if all the VFD comms will slow down the IO?
 
I have not experienced any speed issues in any of our installations. Remember that the bus speed of PROFINET is pretty high compared to "old fashioned" protocols.
 
The important question here is how fast do you need to access the IO? Realistically, though, you're totally fine. PN can go down to at least 250 microsecond update rates on some devices/controllers, but as long as you're OK with an update rate of a few milliseconds you can have quite a few devices. I've seen systems with 50+ robots on PN on top of all the IO drops, and Profinet only took up less than 10% of the overall Ethernet speed capability.

Profinet is built on Ethernet, and uses all those standards. Every Profinet device I've used supports 100 Mbps Full Duplex Ethernet. That means 100Mbps in both directions on each ethernet cable. Profinet also tags all of its traffic as a high priority, so that it will be sent first if a switch gets bogged down by the non-IO traffic.

Granted, I don't know what the limits of your GE module are, but Profinet won't be the bottleneck.
 
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Thanks guys...
I can easily live with sub millisecond responses.
The main critical is one of the analogs for pressure....I am doing a gas back fill to values from this transducer, so I need quick response to prevent overshoot.
 
This topic interests me two. I have a potential customer that wants to talk to 21 motion controllers every 4 milliseconds or so. Our motion controllers can respond with that time easily but I have serious doubts that Windoze can do it even with the fastest of processors.

MK42 has a good point. How fast do they really need the information? Sometime customers have unreasonable specifications.

My thoughts are that a fast PC can probably grab information from 21 motion controllers every 4 milliseconds as long as they don't touch the key board or mouse. I have seen PC Ethernet communications stop while the mouse is moving.
 
Thanks guys...
I can easily live with sub millisecond responses.
The main critical is one of the analogs for pressure....I am doing a gas back fill to values from this transducer, so I need quick response to prevent overshoot.

Don't misunderstand: the PROTOCOL is capable of sub-millisecond communication, but that doesn't mean your hw does. Many analog modules have slowish sampling times, maybe 100ms for all the channels. Even if the modules can talk to the PLC faster than that, it doesn't mean the data is better.

This topic interests me two. I have a potential customer that wants to talk to 21 motion controllers every 4 milliseconds or so. Our motion controllers can respond with that time easily but I have serious doubts that Windoze can do it even with the fastest of processors.

MK42 has a good point. How fast do they really need the information? Sometime customers have unreasonable specifications.

My thoughts are that a fast PC can probably grab information from 21 motion controllers every 4 milliseconds as long as they don't touch the key board or mouse. I have seen PC Ethernet communications stop while the mouse is moving.

Is the potential customer trying to talk Profinet out of the PC? If so, they may need a special Ethernet card to get a good response time. The network can do that no problem, but, as you say, Windows can be silly about what blocks what.
 
Don't misunderstand: the PROTOCOL is capable of sub-millisecond communication, but that doesn't mean your hw does. Many analog modules have slowish sampling times, maybe 100ms for all the channels. Even if the modules can talk to the PLC faster than that, it doesn't mean the data is better.

Very true Profinet wont be the problem for you but its the analog card you need to worry about. Like MK42 stated slow cycle times and bad resolution is still common among many manufacturers of analog cards. If you look at Siemens they offer High feature versions (HF) of their analog cards which is usually enough but if that's not enough they also have High speed versions (HS).

I think this video demonstrates the capabilities of Profinet pretty good. But like previous posters stated a special network card is needed to achieve Profinet RT and IRT performance on a regular PC
 
In regards to PID questions..
I use PID for temperature control not gas backfill. Gas Backfill is set to a setpoint that is monitored by a pressure transducer.
I use a remote temperature controller to handle PID (WAY easier than PLC PID). from the PLC, I send Setpoint and "corrected" furnace temperature to controller and then take %Power out from controller back to PLC to send to Analog Out modules.
In my equipment, temperature change is not "fast", so I can live with sub second comm delays.
I also understand "delays" in Analog module response times.

Also...1 of the VFDs (ABB 550) is on PID for cooling water pressure control, but I am sending pressure to VFD and will probably do PID in VFD. If I do in PLC, I will use internal PID for control. Water Pressure control does not have near as many outside factors affecting PID as temperature does on heat treat furnaces.
 
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I work with pressure/temperature most of the time, as you mentioned, these don't change all that fast.

All of our controllers work on a 100ms cycle, as do the analog inputs. 100ms (and even lower) should not be a problem at all.

As a boiler guy I would love to see what you are making :)
 
I work with pressure/temperature most of the time, as you mentioned, these don't change all that fast.

All of our controllers work on a 100ms cycle, as do the analog inputs. 100ms (and even lower) should not be a problem at all.

As a boiler guy I would love to see what you are making :)

Here is an idea of what my company makes....
This is a "bottom-load" vacuum furnace...or it could be horizontal.
Heats under vacuum and cools under Argon Gas.
Max temp - 2500 F
Ultimate vacuum - 10-6 Torr range.
Cooling pressure range is -5 to 14.5 PSIG (2 Bar)
125HP cooling blower motor.
Completely built and tested at shop, then dissembled, painted and shipped to customer site.
 
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Impressive, thanks for sharing.

What are they used for? I think I have seen something similar where they used it for separating silicon particles (I think) from a cutting lubricant, such that the lubricant could be reused. Or maybe they could reuse the silicon, can't remember :).
 
These furnaces are used for heat treating and brazing of components. Most of our systems go to Aviation and Aerospace customers.
Also "Commercial Heat Treat Companies.... who do heat treat for others.
Vacuum is the cleanest environment available for its affects on metals, you can actually clean inside the "grain structure" of the metal.
You just have to really keep in mind that you are lowering pressure, so you are lowering material vapor and melt point also...

I have seen these furnaces used for everything from knives, forks, and spoons to aerospace rocket engine components for SpaceX.
 
Earlier this year I converted a 90-30 with 12 remote I/O drops over Genius to Rx3i and Profinet. I haven't done any digging into the actual speed, but there has been no degradation in performance since the change. If you want to compare, I can look up the total amount of data exchanged between the CPU and the I/O drops.
 

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