.. _magnalink-masterslave-multirack:

Master-Slave Multi-Rack System Operation
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Multi-rack systems have many nodes connected to the |magnalink| network. To accommodate this extra burden, the communications wiring is electrically isolated and the network traffic is routed between racks.  The MagnaLINK Interface Device (MID-M), acts as repeater, where incoming messages originating from the master rack, *RACK 1*, are parsed and resent to the addressed slave rack, as illustrated in :numref:`fig-magnalink-multirack-diagram`. 

To configure two racks for master-slave operation, use the included RJ11 cable and wire *JT3* in the master rack to *JE3* of the slave rack. *JE3* is on the *Fan Control* board located at the top of the rack.  Connect another RJ11 cable from *JR11* of the master to *JT1* of the *slave*. Master and slaves contain MID-S, which acts as pass-through connections for simplifying master-slave wiring. Finally, connect the red and black *CURRENT SENSE* cable in *RACK 2, SUB 11*, to the common-mode choke located in the master, *RACK 1, SUB 2*.  The instructions given for two rack, can be readily applied to addition racks. All cabinets must be grounded together and all *CURRENT SENSE* cables must connect back to the master rack. Instructions for programming new ratings are discussed in :ref:`software-interface`.

.. _fig-magnalink-multirack-diagram:

.. figure:: /_common-magnaload/_images/magnalink-multirack-diagram.eps
   :align: center

   Multi-Rack System Diagram