Machinery used within the forestry industry needs to be extremely robust and reliable, capable of operating on muddy paths and during heavy rain, and withstanding constant vibrations. An example here is the mobile debarking systems built by Halder, which are used by saw mills that don’t have a permanently installed debarking system on their premises.

Used in several locations in the wooded area of southern Germany, these reliable and robust systems are operated by two workers sitting in the cabin of the MAN truck. From here, the operators manoeuvre long and heavy trunks onto the vehicle where the bark is rapidly removed and the trunks are stacked along the road.

When it was time for a big retrofit, Halder wanted a Profibus fieldbus solution for the machines. For this, Halder and Alois Öhler, a control specialist from R&O, decided to use Murrelektronik’s rugged MVK Metal fieldbus modules.

Not only are the fully potted MVK Metal modules reliably sealed, but additional rubber buffers absorb heavy vibrations. They are also suitable for use in temperatures ranging from -25 to +55°C, although in this application the debarker isn’t used when it gets to –10°C because you can’t strip bark from the trees at this temperature.

During the retrofit phase, MVK Metal’s multi-function ports provided flexibility. “We could use and configure the individual ports as input or output, according to the specific requirements,” explained Öhler. In the end, a complete fieldbus solution was implemented with a relatively small number of modules. If a port is not used, it is sealed with a blind plug. However, this doesn’t happen often as most of the ports are used twice, most commonly for double valve connectors that control the hydraulic pumps. The integrated hex thread on the M12 cordsets is another advantage for Halder. They are able to accurately tighten them with the torque wrench and quickly loosen them for repair work.

Another advantage of the MVK Metal fieldbus solution is that the machine operators are able to troubleshoot problems themselves. If a fieldbus module doesn’t work, for example, they can take a spare module, set the correct addresses and replace the defective module. The automatic topology discovery does the rest. 

Find out more about the MVK Metal fieldbus modules here: Click here to view the video: https://youtu.be/yJsb-HmskKY?list=PLKJNX0EVtrXQtmWug4yQ14ELQkTflnLrE

Read the full story about the machines in Design Solutions June:  http://content.yudu.com/A3qdi8/DSJune2015/