# Sercos servo drives with ControlLogix?

M

#### Mike

Interested to know if anyone has experience with using servo drives (other than AB's line), with the ControlLogix Sercos Motion control system. I am particularly interested in using PacSci drives. If so how hard wwas it to setup?

J

#### James Ingraham

According to A-B, it is not possible to use third party drives with their current SERCOS system. This is because they essentially ignored
everything about the SERCOS standard other than the physical layer. When I asked them if they would ever support third party drives they
said "Maybe someday."

-James
Sage Automation, Inc.

M

#### M Fugere

Hi Mike,
Currently R-A does not support non R-A/A-B drives
on our ControlLogix SERCOS system. The reasons for
this are rather complex, but rest assured that the
SERCOS "standard" does not imply nor guarantee
consistent performance or capability among multiple vendors' SERCOS products.
Using our own drives we have been able to achieve a high degree of integration, consistency, and "plug-n-play" like capability in the Logix control system. IT was not possible for us
to provide these levels of functionality with just any vendors' drives, as the capabilities and functionality of the many available SERCOS products vary tremendously - ask anyone who has tried to implement more than (1) vendor's
SERCOS productin an application. Usage of the R-A drives do not require you to even know anything about SERCOS or IDNs to set them up and you can achieve "run out of the box" capability with this integrated system - we think that it is a significant advantage. Just as you cannot use
your AOL software to connect to Compuserve (they are both "internet standards" but they each have properietary protocols stacked on the IP layer) there are many variabilities in the SERCOS standard which do not provide 100% compatibility among different providers. But if you use AOL with AOL or Compuserve with Compuserve you can surf the net just as easily one way or the other.

The SERCOS vendor community is working to improve
this situation, and Rockwell Automation is part
of that community. Since it is a global community, somethings take time, but we are working on it.

Hope that this information is helpful to you.

Best regards,
M Fugere
Rockwell Automation
IMC Engineering Mgr/Controls & Software

B

#### Brian Rode

This question brings to light AB's excellent Marketing ability to take a standard communication platform and twist it in to something proprietary. But the good news is that you can match them at their own game. You can
actually use a Devicenet drive to achieve an open motion control package. That will perform better than their half-breed Sercos attempt. Just for the record the API/Pac Sci PC3400-DN divicenet drive works excellent on Controllogix's divicenet card, but guess what "no" fiber optics to deal with. The Devicenet card runs for like $975 instead of$1500 for two axis. I am so impressed by the functionality of Devicenet in this application. My hat is off to AB for developing Devicenet and would welcome their comments on using Devicenet verses Sercos.

Just my view

Brian Rode

M

#### M Fugere

Hi Brian,

Although we are drifting off the original topic
here, I will respond to your questions/issues.
If you would like more detailed information, we
can take the email dialog off line.

> This question brings to light AB's excellent Marketing ability to take a standard communication platform and twist it in to something proprietary.

Response: Perhaps my earlier analogy wasn't the
best one. R-A's ControlLogix SERCOS *IS* SERCOS.
We use the same ring phases, standard IDNs, etc.
as other vendors SERCOS products. We also use
some proprietary IDNs - per SERCOS standard and just like other vendors do as well. Currently, we require certain Proprietary IDNs to identify our drive and facilitate commissioning/hookup, etc. Other vendors products may interpret those P IDNs numbers differently or not at all, which is
acceptable per standard. Other vendors systems
also employ this mechanism, and it complicates
the ability to use Vendor B's drive on Vendor A's controller where both vendor A and vendor B make both drives and controllers.

We have found that various SERCOS products have
significant differences which affect how many
nodes can be supported on a ring: cycle times, length of AT, IDNs allowed in the AT, baud rate,
etc. etc. Many of our R-A customers demand guaranteed performance, number of axes per ring,
servo loop types supported, baud rates, etc. from R-A products. We found that it was extremely difficult for anyone to make these sorts of
guarantees without imposing limits on the drives
they used on the SERCOS ring. Perhaps you have
observed this sort of situation in real life ?
Can you guarantee that your IEC1131 compliant
program will work perfectly well on a machine,
regardless of the PLC it is running on, it's
processor CPU power/scan rate, and memory size ?

>That will perform better than their half-breed >Sercos attempt. Just for the record the API/Pac >Sci PC3400-DN divicenet drive works excellent on
>Controllogix's divicenet card, but guess
>what "no" fiber optics to deal with. The >Devicenet card runs for like $975 instead of >$1500 for two axis. I am so impressed by the >functionality of Devicenet in this application. >My hat is off to AB for developing Devicenet and
>would welcome their comments on using Devicenet >verses Sercos.

Response:
The DeviceNet drive may be perfect for some motion
applications and not for others, and this is
a very application dependent question. Indexing
drives on DeviceNet can work well for what we
would consider a basic motion app, but if you
required a larger number of tightly coordinated
axes, perhaps with mechanical interaction and/or
with very rapid, coordinated response like in a
high speed packaging web application with registrations, the axes need to be more tightly
synchronized and connected to (1) motion planner
group executing in the Logix processor. This
synchronization and coupling is currently only possible with servo axes when using them on
an M02AE (analog) or M08SE (SERCOS) module.
The DeviceNet card and anything hanging off it
is treated as scanned I/O, and will have a
slower update rate and will not be tightly
synchronized with the motion planner or the
servo axes which it controls directly. Again,
it is all very application dependent.

>
>
> Just my view
>
> Brian Rode

Response: I hope that I have been of some help
in shedding some light on these topics. IF you
desire more detailed info I would strongly
suggest we go off list.

Best regards,
M Fugere
Rockwell Automation
IMC Engineering Mgr/Controls & Software

S

#### Scott

Watch out for Pac-Sci/API 3400 series drives. They have shipped alot of bad units with mismatched firmware. We have had extremely bad service from pac-sci