Hello all,
Thanks Graeme for your input, quite detailed.
We made a controller prototype with advantech TPC-1251T . We put it on 5
machines.
Linux with etherlab ethercat master, EK1100 as slave with digital and
analog IO, gtk3 as hmi (touch screens are hard to configure on linux).
The processing is running with realtime flags, hmi is not.
Cycle time around 3ms.
When needed, safey is using a "cheap" omron safety controller,
communicating using RS232 with linux for additional info.
Otherwise, safety relays.
Uses CFast cards, shutsdown directly, without UPS.
The first one installed 6 years ago, had to change the motherboard
battery (spends a lot of time without power).
Never had a card corruption.
It was a proof of concept and we had the opportunity to try linux and
etherlab.
I think these solution are only profitable if it is a very special
machine, or a serial machine, or if we can (our case).
The biggest advice is to structure your application well, keep in mind
that slow tasks will slow your process overall.
So, no hard disk reads or writes, communications or what so ever in the
process task.
Best Regards,
Luis Matos
Às 23:14 de 26/11/2023, Graeme Foot escreveu:
Hi Nicola,
We've been using Beckhoff CX2020's for around 12 years on over 300 machines
running at 1000Hz (1ms). They are now end of life'ing so have nearly completed
updating our system to be able to work with CX5230's (needed new Linux kernel
etc). They are a bit slower than the CX2020's but have the power we need for
our machines. We run them headless connected to a Windows HMI PC.
If we need more power or a faster cycle in the future we've also briefly tested
the new Ryzen CX2033 which looks like it runs around 3 times faster than the
CX5230 for our system.
We build our system using Buildroot with the EtherLab EtherCAT master and RTAI.
We've never used an arm based CPU, just x86 (and now x86_64).
So, the Beckhoff PC's in our experience are fine for Linux. Each system has an
order code for purchasing it with a blank disk (aka no operating system or
TwinCAT). You just need to get past the hard sell. Of course you are on your
own once you buy it if it's not a hardware issue as they know nothing except
TwinCAT, but that's the case with any PC you go with.
A summary of our system:
* CX2020 (soon to be CX5230)
* Linux 2.6.32 32bit (and now Linux 4.19 64bit)
* Our application uses approx. 21-35% of CPU time @ 1000Hz on CX2020 (25-63% on
the CX5230, slower CPU and 64bit is a bit slower than 32bit Linux)
* RTAI
* thttpd to provide a web based configuration and diagnostic interface
* The majority of the root filesystem is provided by initrd with mount points
for a small amount of config files that need permanent storage (CFast cards).
So very minimal and infrequent HDD access and no problems with power outages or
storage corruptions. On a normal machine shutdown we do send a halt command to
Linux to be nice. We have had one CFast card release it's magic smoke, but we
don't know why, we suspect it was a hardware failure.
* A couple of decades ago we had UPS's on a few machines, but the UPS's would
fail more often than there were power cuts. Also our machines can't do
anything without power, so for us its just better to let the system turn off.
* We've used FSoE on four machines (using the EK1960 and various other TwinSAFE
modules). It was a machine with complex safety requirements (light curtains,
deadman switches, bypasses plus other). I wrote a Mailbox Gateway server for
the EtherLab master so you could download the safety program to the TwinSAFE
PLC (using the TwinSAFE Loader program supplied by Beckhoff) via the EtherLab
master. We looked at the costings of FSoE vs a standard Safety Relay on our
standard machines a while back and although it was close FSoE was more
expensive and more complex so we stayed with Safety Relays.
Regards,
Graeme
-----Original Message-----
From: Etherlab-users <etherlab-users-boun...@etherlab.org> On Behalf Of Fontana
Nicola
Sent: Friday, November 24, 2023 9:37 PM
To: etherlab-users@etherlab.org
Subject: [Probable Spam] [Etherlab-users] Embedded PC with out of the box
support for igh-ethercat
Hi all,
I'm in the process of trying to "standardize" the hardware stack I'm using
My requirements are:
1. a PC easily connectable to EtherCAT
2. native support for igh-ethercat
3. OPC/UA server via open62541
4. reliable 5 ms scan time
Lately I'm using Beckhoff CX9020-0100 but its performances are (mildly
put) crap. I fear to use other Beckhoff solutions because they seem to not
support Linux natively (the fact that they keep pushing for TwinCAT is quite
annoying).
I am also quite interested to know what do you use in general, how do you
handle power outages (or more general the poweroff procedure) to avoid storage
corruptions and if you use FSoE. Those would be a really great FAQs.
Thank you.
--
Nicola
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