VUTRAX Application: Measure

The Analogue Class Gap: Vutrax Gives Designers the Edge at Chronos Richardson

The turnkey weighing systems manufactured by Chronos Richardson find applications wherever solid ingredients have to be mixed by volume, whether it is a flour mill, rubber compounding room or fertilizer factory. The Nottingham company, which is part of the Staveley Industries Group, also builds its own controllers, using Vutrax ECAD software for all PCB design work.

The process control specialist has been using Vutrax, from Computamation Systems Ltd., since 1984 when it made the switch from tape boards. Huge time savings resulted, with the ease of modification a particular benefit, according to Martyn Lennon, Senior Development Technician. "The top down modify feature means that what a designer sees in his schematic diagram, he gets in the artwork."

The company also uses back modify, providing a complete loop in the amendment process. "If you find that routing will be easier with a pin swap you can back modify that swap into the circuit diagram", explains Mr Lennon. "Without it the designer would have to check the artwork against the schematic pin for pin."

Chronos Richardson, which has a second plant in Germany, is one of the leading manufacturers in its field. Its turnkey weighing lines can cover every process requirement, from loading and balancing to bagging. Weights covered range between 10-50kg, when bagging fertilizer ingredients for example, to five tonnes for the loading of ships. In each case, the controller provides the automation intelligence.

All PCBs are designed in-house, contracted out for manufacture and returned to be sourced and populated. The company uses multi bus boards, with a maximum of six layers including the ground plane. Up to 90 ICs are used on a board, ensuring a tight squeeze in most cases.

The company uses amplification by load cell with strain gauge technology and processes this output into digital signals. Analogue work is important and according to Martyn Lennon, the class gap facility has been a valuable feature on the ECAD software.  "With the class gap feature we can specify the minimum spacing between various signal names which helps to keep things separate on analogue boards, and also helps us build the inner layers if we are using a groundplane. It becomes very easy to isolate the inner layers to keep components with different power inputs away from each other."

The electronic design department has in-house rules on component placement and out of personal preference, Mr Lennon places manually. He says the tracking density histogram, which highlights potential trouble spots, is a useful guide when finalizing the layout. All boards are then routed automatically.