MagnaLINK™ is a low-level high-speed communication protocol designed by Magna-Power Electronics to expand functionality in the presence of multiple products, support real-time control, and handle multi-processor firmware upgrades.

5.1. Network Overview

There are three types of communications that the main control processor manages using three independent ports. On Port A the processor manages internal processor-to-processor traffic. Connected to this bus is the gate drive processor, which is responsible for power controls and protection. Also connected are the auxiliary power supply processors, which power all other boards, cooling fans, and solenoids. These processors are critical to the operation of the MagnaLOAD electronic load; hence, communications on Port A bus are not exposed. Port B carries product-to-product and the front display processor traffic. The port is exposed through two RJ11 connectors located in the back of the product. Connections to the front display are made internally to the product. Port B is designed to handle more network nodes and has programmable termination resistors to dampen transmission-line effects. When connecting two products use only the Magna-Power Electronics supplied MagnaLINK™ cables. Front display boards are also connected to Port B to support remote-panel operation. Port C connects to external devices such as computers. The port defaults to SCPI protocol on start. Magna-Power Electronics software switches the protocol to MagnaLINK™ which contains the full set of commands available to MagnaLOAD electronic load, is lower overhead, and faster speed.

5.2. Master-Slave Module Operation

When MagnaLOAD electronic loads leaves the factory they are programmed with a fixed voltage, current, and power rating corresponding to the model. When multiple MagnaLINK™ compatible products are connected together, new ratings must be programmed for higher-power operation. If the detected power rating does not match the programmed power rating the product enters into a hard-fault condition. This rating check was added so that if any of the modules in the MagnaLINK™ chain are disconnected or fail, the customer can be notified, and take corrective actions. The instructions that follow explain how to wire slaves modules. The process for removing slave modules is identical to adding slave modules.

All MagnaLOAD electronic loads need to be powered off by moving all front rocker switches into the off position. One MagnaLOAD electronic load will be designated as a master all other MagnaLOAD electronic loads will be slaves. On the master, connect the supplied MagnaLINK™ cable from the RJ11 connector labeled MAGNALINK OUT to the slave connector labeled MAGNALINK IN. Connect the red and black Molex 1545 terminated cable from the MagnaLINK cable kit into the white, Molex 1545 Series plug, labeled CURRENT SENSE, in the back of the master and the slave units. After all the described connections have been made, turn on the rocker switches. Instructions for programming new ratings using are discussed in MagnaWEB.