Questions to be considered before installing a Fieldbus system
When opening a discussion on Fieldbus as a customer, the following prompts will help everyone to gain an understanding of the system requirements and the most suitable Murrelektronik product that will best serve your needs.
Murrelektonik explain just what a Fieldbus Prompt is and also how Fieldbus Prompts work and perform.
Firstly, it is important to determine what you as the customer actually do:
i) Are you a series machine builder, bespoke machine builder or a system integrator?
ii) If any, what is your specialisation (i.e. Packaging machines, filling machines, pick and place machines, material handling etc.)?
After establishing the type of machine / system, it is important to understand as much as possible about the application. In particular:
i) Are the machines considered ‘high speed’?
ii) Do they use drives and servos?
iii) Do they measure analogue values (e.g. temperatures, pressures etc.)?
These answers should help in narrowing down the I/O products that can be offered.
After gaining an understanding of the ‘business’, we must then address targeted questions, such as:
Do you have a specific control platform for your machine / systems?
If yes, why was that particular control platform selected and was it intended to be adhered to for new machine developments? It is important to remember that Murrelektronik can offer I/O products for connection to most controllers.
Some machine builders, particularly series builders, will have developed their automation system around a specific PLC/PC Control platform. Similarly, some system integrators also specialise in a specific manufacturer’s controls, sometimes referred to as a ‘Siemens integrator or a Rockwell integrator’ etc.
Other customers may claim that they use whatever their customer (the end user) specifies.
In this case, we need to understand:
What do you find to be the most specified control platform?
If the answer is Siemens and Rockwell, this is important, especially with the compatibility of the Cube 67/20/20s range.
After this, it is important to note:
Are there many projects where the specification is ‘open’ and you can select the control platform?
Is it likely that the answer will often be ‘yes at times’, as this is usually the case. Thereafter, we must ask you to consider the following:
What product does the customer prefer to use when not constrained?
The answer to this will establish your preferences. Once again, Siemens is excellent for integration with Murrelektronik products, Rockwell is very good also and although far eastern manufacturers can sometimes present integration problems, these issues are not impossible to resolve.
Have you considered using remote I/O?
If the answer here is yes, then we must understand what Fieldbus system is used? If the answer is no, then why has it not been considered?
Yes – What Fieldbus System is Used?
If Siemens is specified, it will most likely be the Profibus and/or Profinet Fieldbus that is used. However, if Rockwell is preferred, it will be EthernetIP (and possibly Devicenet) that is used.
No – Why has it not been considered?
Possible answers include, but are not limited to:
i) The machine is too small
ii) We have not got round to it
iii) More bother than it is worth
iv) Our customers don’t like it
v) The cycle time is to slow for our application
Other than possibly the cycle time, the remainder of the reasons may be due to a previously bad experience in the past (often experienced a long time ago). If there is a hidden objection, it is crucial that you find out exactly what it is that needs to be overcome.
At this stage of the process, it is useful to understand the machine/application. If you are a fieldbus user, what I/O are you using, since in most cases Murrelektroniks can offer both a better technical solution and many cost savings.
However, if you are not using fieldbus, it is important to establish whether remote I/O will offer a more cost effective solution.
You will need to look at the application holistically; including the device’s (sensors/actuators) locations on the machine, the cable routes back to the panel or I/O module and the connectivity. Take a look inside the control panels to see what type of equipment is being used.
Several customers will have an I/O list which lists the I/O for each location and the I/O type (e.g. DI, DO, AI, AO etc.).
It is important to convey as much information as possible. If time is at a premium or you are unsure, it is important to agree a time and date for a machine survey.
When trying to select the most appropriate Murrelektronik solution for your application, the following rules should be considered and applied:
• Profinet, Profibus and EthernetIP – have the widest range of products available, including Cube 67/20/20S, Impact 67/20 and MVK.
• Ethercat – Be careful with Omron controllers and be sure to collect all the information so that you have a reference point.
• Analogue signals – Cube 67/20/20s and MVK only.
• IOLink – Always ask why IOLink is being considered. Is it because you would like to use IOLink sensors due to its benefits, or have they been sold as a ‘cheap remote I/O solution’, because if so, the Cube family of products can offer a far better solution. We can offer IOLink with Cube 67 and MVK (Only with Profibus and Profinet).
• ASI – Always check if analogue control is required and to what extent.
Remember, if you need more information, feel free to ask. There is no such thing as a daft question, just daft answers.