4.1. MagnaLINK Master-Slave

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.

4.1.1. 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 MagnaDC power supply; 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 MagnaDC power supply, is lower overhead, and faster speed.

4.1.2. Master-Slave Multi-Module Operation

When MagnaDC power supplies 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 MagnaDC power supplies need to be powered off by moving all front rocker switches into the off position. One MagnaDC power supply will be designated as a master all other MagnaDC power supplies 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 MagnaCTRL.

4.1.3. Master-Slave Multi-Product Operation

In section Master-Slave Multi-Module Operation we describe the process for a single-product system that is factory-wired with multiple modules. In that case, modules are fixed in a rack, wiring never changes, and the system is calibrated in that known state.

Multi-product operation involves connecting multiple products together at the customer’s discretion. While this provides great flexibility — allowing customers to scale power on their own — it reduces certainty about wiring and master-slave ordering. The analog input/output signals carried by the MagnaLINK and Current Sense cables can be susceptible to shifts from the factory calibration due to differing wire lengths and slave ordering, which can necessitate recalibration. By following the master-slaving setup recommendations below, customers can mimic the factory’s master-slave calibration and minimize additional calibration at the installation site.

When customers order multiple products intended for master-slave configuration, additional factory testing is performed. Products are wired together starting with the highest serial number (master) and continuing to the lowest serial number (last slave). The calibration gains saved in the EEPROM are based on this ordered configuration; if the customer follows the same master-slave ordering convention at the installation site, calibration shifts will be minimized. Additionally, customers should use the MagnaLINK and Current Sense cables included with their shipment. The grounds for all products should be tied together via the chassis stud located near the AC line inputs on each product. Keep the MagnaLINK and Current Sense cables routed away from AC line wiring.

The expectation is that the number of MagnaLINK cables aligns with the number of products the customer plans to configure as master-slave. If this is not the case, customers should clearly communicate the desired configuration with Magna-Power Electronics sales and support.