Real time Ethernet in injection moulding machines of Arburg
Real time Ethernet, as standardised interface for drives, sensors, IO modules and safety components, is now state of the art. The economic crisis is delaying the market penetration in many sectors of the machinery industry but existing solutions will be replaced step by step in the future.
"Right" system - difficult to determine
The approach to the sound decision
A reasonable approach is to specify the requirements of the application, the system or the machine according to priorities and then to compare the different systems using a decision matrix.
Arburg, one of the world-wide leading manufacturer of injection moulding machines, used this approach evaluating among others nine criteria for selecting a real time Ethernet system.
1. Open system?
Is the system open and manufacturer independent? This means that manager and client can be implemented as FPGA firmware or an ASIC solution of several manufacturers is available?
2. Flexibility?
Does it offer a flexible topology such as star, tree, and line in every combination?
3. Low jitter?
Can small packets, typically 36 bytes, be transmitted fast and with low jitter?
4. Robust system?
Is the system robust? Crucial in this connection are:
- Protection against manipulation or trouble for example by inadvertently plugged in standard Ethernet participants?
- Safe data communication by repeated telegrams within the same cycle
- Watch Dog functionality with defined reactions
- „Hot Plug and Play“ - ability.
5. Boot and update via network?
Can system boots and software updates be realised via network?
6. Access to each participant?
Can a simple diagnosis with direct access to each intelligent participant take place?
7. Simple addressing?
Is a simple addressing without rotary or DIP switches and without IP address for each participant possible?
8. Easy connection to the control level?
9. Cost-effective and available?
Is the system cost-effective, established on the market and thus the components accordingly available?
Arburg convinced of Varan
After thorough evaluation and extensive tests Arburg decided for Varan. Since October 2008 Varan is implemented at the robot systems, the Arburg injection moulding machines can be equipped with. Since then Varan has been proving as fast, robust and safe system in the series. So the use of Varan is extending on further components such as drives and sensors of the injection moulding machines.
System independent benefits - benefits for all...
System independent device profiles for different groups of components have been now accomplished. This opens up development safety, reduction of the time-to-market and substantial cost savings to the related component manufacturers.
...including with Safety bus
Such a system independent approach is desirable also in the field of Safety bus, in which almost any system supplier pursues its own concept. So immense investments as well as lengthy tests and release processes are emerging.
This is why the industry and above all the manufacturers of safety components should push for standardised protocols. Whether the safety protocol will be wire-bound or wireless and which real time Ethernet systems will transmit the so-called „Black Channel“ is not relevant in this context.
Crucial for the safety protocol are the attributes safe, robust and standardised!