CAN in Agriculture
Holmer Maschinenbau GmbH is a producer of innovative special machinery for agriculture. One of these special crafts is the Terra Variant. This machine can be used in a broad field of applications like the spreading of liquid manure or the applying of fertilizers. In addition it is also a suitable cargo truck when turnips, corn or crop are harvested. For the turnip and corn harvest a bunker volume of 35-40 m³ is available. If turnips are stored the bunker is emptied in 60 seconds, in case of corn it takes 160 seconds to deplete the load. For data transmission between user terminals, joysticks and valves plus the monitoring of sensor data among others the Controller Area Network (CAN) is used. The Terra Variant is 10,25 m long and 3,98 m high, because of these dimensions bus lines of more than 15 m are necessary to control accessory equipments. If all bus nodes are connected to a data line, the overall system is more sensitive to interferences. For Holmer Maschinenbau the reliability of its machines is essential, thus a cost effective way to increase immunity against interferences was needed.
In these days the CAN Repeater CRep-N was already a part of the EMS Dr. Thomas Wünsche product portfolio. CRep-N is able to separate a CAN bus line into two physically disconnected bus lines. This increases the immunity against interferences of the overall system and eases maintenance of a complex machinery like the Terry Variant. This is an important factor in the agricultural applications, because the dominating strong environmental influences can cause mechanic damage or break the lines. In this case a separation of the bus line helps to identify the broken bus node. For linear bus structures the EMS Dr. Thomas Wünsche products CRep-DS-102 and CRep-N provide this advantage. If a station has a big number of CAN Nodes, a star topology based solution is usually the better choice. This structure can be implemented with the star repeaters CRep-S8C and CRep-S10i.
CAN-Repeater CRep N
The assembly rail mountable CAN repeater CRep N transmits and amplifies CAN signals in a protocol transparent way. CRep N allows the design of flexible wiring topologies. Star and tree structures as well as stub lines can be realized. The maximum dat…