Friday, August 29, 2014

COMbricks - the vaccine for the "PROFIBUS Virus"


Sometimes the intermittent and unexplained failures of a PROFIBUS network can only be explained as one thing: "my system has caught the PROFIBUS virus!"This is how it must appear to someone who doesn't have the right tools to analyse and monitor what is going on with the network. It is important to realize is that an error, on a PROFIBUS network, does not necessarily mean a system failure. A classic statement that our PROFIBUS Engineers receive on arriving to troubleshoot a PROFIBUS network is: "but it was running fine for all these years - why does it fail suddenly now?" To answer that question, you can think of it this way: does a person die the moment they have a cough? Maybe a bit of a drastic analogy, but the answer is of course not! 
The person will go to the doctor for a checkup, who uses his tools to listen and see what is going on.If his symptoms are left unattended, then the outlook might not be so great. PROFIBUS is robust though! You need to violate installation rules, quite seriously, for it to fail.

Just a like a person goes for a health checkup, so too does a PROFIBUS network need a health checkup!

PROFIBUS users also have tools available that can help them do a "checkup" on their network. ProfiTrace is just such a tool - it tells use if there are any illegal/corrupted messages on the network, if there are malformed signals with its ScopeWare and can even generate reports based on this. Sometimes though, the errors (which are not failures) are very intermittent and happen when the test tools are not connected! You also want to know the moment an error happens - before they accumulate to cause a system failure or plant trip. 

Imagine we could have a doctor permanently connected to us and tell us tell us something is wrong the moment it happens! This obviously isn't possible, but it is possible for PROFIBUS! COMbricks can be connected to your PROFIBUS network and is listening for any errors before they cause a failure. The user can go investigate the cause of the error and take action. Preventative maintenance is kind-of-like taking a vaccine - it prevents you from getting sick. 

A local steel-cutting factory in South Africa sees the value of this. They are using COMbricks to monitor their line for any errors which may lead to failures. The following issues have all be detected on this line using a combination of ProfiTrace and COMbricks:
  • Termination errors
  • Faulty devices
  • Corroded PROFIBUS connectors (bad earthing)
  • Bus cable to close to high voltage lines
They realize that being able to prevent failures is well worth the outlay of the initial hardware cost. It makes sense to buy equipment that will pay for itself. For a site such as this one, preventing a single plant trip is worth much more than the cost of this extraordinary piece of hardware. 

The above image shows the COMbricks headstation getting a firmware update with the latest features before being commissioned. Such a tiny device with a huge responsibility! 

In the picture on the left COMbricks is not only monitoring the health of the PROFIBUS network, but is also acting as a PROFIBUS  repeater. 

Contact the IDX, who run the PROFIBUS Competence Centre of South Africa, if you'd like to find out more visit www.idx.co.za or call them on +27 11 548 9960



Wednesday, August 27, 2014

Certified PROFINET Training in South Africa

Certified PROFINET Engineers Course in South Africa

The PROFIBUS/PROFINET Competence Centre of South Africa recently ran two Certified PROFINET Engineers in a row at Siemens South Africa.
Using tools such as Netilities from PROCENTEC, the delegates were able to quickly understand the structure of their PROFINET network. They are able to configure their devices to match their setup in the controller. Configuration of the S7-1200 PROFINET controller from Siemens is done in TIA Portal.


Migrating from PROFIBUS to PROFINET is covered in the training and is shown to be quite seamless with COMbricks from PROCENTEC.
In addition to this, COMbricks users can permanently monitor their PROFIBUS installation. Remote access and alarms are also possible. The modular nature of COMbricks allows the user to add slave, IO, fibre optic, PA, scope and repeater modules.
Tapping into the network teaches the delegates the fundamentals of the PROFINET protocol. Start-up procedures and diagnostics messages are recorded using Wireshark, a tool that the delegates get to configure to suit it for PROFINET applications. To capture these messages delegates connect the provided laptops to the network switch and enable port mirroring. ProfiTap from PROCENTEC allows the user to capture messages, verify connections and performance of IRT applications. It works really well with the Netilities tool mentioned above.





What if you don’t have PROFIBUS or PROFINET?
Anybus X gateways allow you convert between other fieldbuses and industrial Ethernet Protocols. Getting a Modbus device is easy with the Anybus Communicator from HMS. You’ll find these on the training rigs too.

The training was well received, and the delegates all received an International PROFINET certification and will soon be able to find themselves listed amongst the elite PROFINET Engineers listed at PROFIBUS/PROFINET International. In addition to that, they are entitled to 3 CPD points if they are registered with the Engineering Council of South Africa (ECSA). For more information, send an email to academy@idx.co.za

Choosing the right PROFIBUS cable

Choosing the right PROFIBUS cable
Is the application PROFIBUS DP or PROFIBUS PA?
My cable is purple, can I use it?
DP cable has a 150Ω  impedance
PA cable has a 100Ω  impedance
RS485, CAN bus, DeviceNet and other data cables can be purple in colour but have a 120 Ω impedance
So what if my cable impedance is wrong?
PROFIBUS devices and their terminations are designed to match specific impedance.  Your data signal will degrade and your waveforms will be malformed.
Use a test tool like PROFIBUS Troubleshooting Toolkit from PROCENTEC with built in scope function to check your signals

The T1 Pepper Active Terminator matches can sort our any impedance mismatches