SCH2 Technical Manual TSP016.doc Issue 3.0 – January 2005
Money Controls 2005. All rights reserved.
Page 46 of 61
17. Power Distribution on a Multi-Drop Bus
The multi-drop bus for Serial Compact Hoppers consists of a power, ground and serial data line.
When more than one hopper is attached to the bus, all power is transferred along a single cable
and significant ground potential rises can occur.
The following recommendations are made…
¾ Only operate one serial hopper at a time. Never initiate a second payout
sequence when one is already in progress.
¾ Consider the use of signal conditioning on the serial data line receiver.
Perhaps a high-frequency filter and voltage comparitor input with a mid-rail (
2.5V ) threshold.
¾ Consider running separate power cables to the hoppers to alleviate the
ground potential problem.
¾ If communication errors still occur, consider changing the topology of the
multi-drop bus network. A star network will distribute power more evenly than
a ring, tree or daisy-chain network.
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