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WattMaster WHP Section 4
Start-Up and Troubleshooting 4-1
1.0 Communications
Over view
Perhaps no other portion of the system seems as difficult to diagnose as the communica-
tions loop, yet it really can be quite simple if you understand how it works. In fact, much
of the troubleshooting can be done by simple observation. We will lead you through the
system functions and then provide you with detailed instructions for checking each piece
of equipment.
1.1 How It Works
WattMaster uses a token-passing loop architecture, which means in simple terms that an
“electronic message” called a token is passed from controller to controller in a round-
robin fashion. A controller must wait to receive the token before it can send or request
any data.
Note: It is very important to know which device is the loop master on the loop
you are troubleshooting.
1.2 WattMaster WHP System
The standard WattMaster WHP system may have only one communications loop or as
many as thirty communication loops depending on the number of WHP Controllers to be
connected to the system. It is important to remember that each loop must have its own
master.
If you are using the multiple loop version of the WHP system (for systems with more than
30 WHP Controllers) a loop is required for each group of 30 WHP Controllers. The WHP
Loop Controller may be connected to any of the Local Loops. The Local Loop that has
the WHP Loop Controller installed can only have 29 WHP Controllers on that loop. Each
Local Loop is connected to a MiniLink loop interface. The MiniLink is always the
master on the Local Loops. The MiniLinks are connected to the CommLink II and to
each other via the Network Loop.
The CommLink II is always the master on the Network Loop. You must be sure the
CommLink II is connected and functioning if you are troubleshooting the communica-
tions loops. Make sure the CommLink II is set for multiple loops
.