Comparison between Profibus-DP and Interbus

  • Thread starter Ali Reza Fereidunian
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Thread Starter

Ali Reza Fereidunian

Here, we are designing three robotic manufacturing lines (welding and material handling Kuka robots). We are to make decision about the type of networks to communicate between PLCs, robots, and instruments. We have 3, 9 and 12 robots in three individual lines. Our choises are Profibus-DP (using CAT5 UTP copper cable) and Interbus (using fiber optic medium). what do you recommend for this situation?

Thanks and regards
Personally, I would be happier with Device Net but that is a decision you will have to make from your evaluation. Here is a link to the Device Net Vendors Association where you can find most things Device Net and Ethernet/IP. That would be my second choice.
Here is a very good fieldbus page where there is information on most fieldbusses


Donald Pittendrigh

Hi All

If you are restricted to Profibus on CAT5 cable, I would suggest that would be an extremely bad choice, as you are quite unlikely to get it working properly on this cable.

Investigate the new Profinet, which is profibus on Ethernet, do not use cat5 in industrial applications, it has no screening or EMI protection, check the Siemens web site for ITP or industrial twisted pair, it is one of the best industrial solutions.

As to the comparison, I should think the decision would resolve to which of the two bus systems would move data faster and more reliably and I doubt if Interbus will show better specs than 12Mbyte Profibus, but the question is well worth asking.

Regards Donald Pittendrigh
If you genuinely have a free choice of network to cover your PLCs, robots and instruments, then you are very fortunate indeed. Very often the choice will be limited because a manufacturer in one of these categories will only support one particular network interface, which then constrains all other selections.

If you still have to select the suppliers for the PLCs and instruments (you only mention specifically the manufacturer of the robots) then I would go for Profibus. The range of manufacturers who can support an interface to this is enormous. There are also many examples of Profibus being used in welding & material handling applications so you are not stepping out on your own.

However, I would NOT recommend CAT5 cabling! Either use correct Profibus-DP copper cable according to the Profibus Organisation specification, or, since you appear to be considering fibre-optic, go for Profibus-DP over fibre. This latter gives supreme noise immunity (maybe important in a welding environment) although the skill set for installing and cutting/joining FO cable is quite different from standard copper.

Good luck whatever your final choice.


Ken Muir

Armin Steinhoff

If these individual lines have to work indenpendently ... choose PROFIBUS-DP. If these lines are functional dependent ... you could also use Interbus.

I can also imagine a configuration with Interbus for the individual robotic lines (if a time resolution of 1ms is good enough) and PROFIBUS-DP for the communication between the lines.

Best Regards

Armin Steinhoff

Linnell, Tim

(1) CAT 5 cable is not compliant with the Profibus standard, which specifies two cable types. You can use it, but you'll need to frig terminator values and generally will give yourself problems.

(2) Profibus DP is only a good choice if you have a central master allocating data to slaves and collating input data from them. In this case it is probably also the best choice, as it's fast, runs like clockwork, and is easy to understand and maintain. Interbus would work reasonably in the same style of system, but is more limited in terms of the devices you can buy and connect (my view is that Interbus has been rather vanishing over recent years).

(3) DeviceNet would be a very poor choice in this application. Although notionally peer to peer, most devices are group 3 only servers (slaves), so you get the disadvantages of needing a central master as above, with a very slow update rate (500K) and throughput problems due to the fragmentation of data into 8 byte packets. Works well for small networks; the word on the street as I have heard it is that AB use their own proprietary protocols (DH) for their own systems in preference.

(4) Last time I looked (and I'd be glad of an update here) Ethernet/IP used a protocol stack requiring a VXWorks style RTE supporting 22 concurrent tasks. Quite limiting in terms of devices that can be supported, and it appears to me that Modbus/TCP is the de-facto ethernet standard at present (any comments, anyone?).

(5) CanOpen may be a reasonable choice - good number of devices and it uses CAN well to provide real peer to peer comms.

Generally, fieldbus network choice comes down to the number of devices suitable for your application available supporting a candidate network, and the required topology and data transport model. In most cases where there's a central PLC + distributed function (drives, I/O, temperature control instruments, etc) I would personally use Profibus DP every time.


Tim Linnell (Eurotherm, but all comments and views are my own!).

Ali Reza Fereidunian

Thanks for your helpful comments.

Mr. Pittendrigh,
We decided to use Profibus. But I must be careful to find a good substitude for CAT5 cables as you have mentioned. I will try the ITP, that'll be very kind of you to introduce me another siutable cables.

Mr. Muir,
We have decided to use Profibus and as you have mentioned we must be careful about the kind of cable we use. That'll be very kind of you to recommend me a specific type of cable and its source.

By the way, do you know that ARMIN is a persian (Iranian) name?

By the way, perhaps I attend at a training course for Eurotherm Controllers in UK in coming September.

Best regards,

Ali Reza Fereidunian

Dear Tim,

Thanks for your help ful comments. Which kind of cables do you recommend instead of CAT5?
By the way, perhaps I attend at a Eurotherm Controllers training course in UK in the coming September.

[email protected]


Linnell, Tim

Belden do specific Profibus cables, as do others. The best thing to do is to visit and look in the on-line product guide there.

It is in fact possible to use CAT5 in tightly constrained circumstances, with specifically tuned termination networks (but this is not standard Profibus DP). We use this for internal cabinet wiring between some of our systems products.

If you're in Worthing for the Eurotherm course, I may bump into you (and that goes for everyone else on the A-List, since obviously **everyone** should attend a Eurotherm controller course... ;-))

Best, Tim Linnell