Pathway DMX Pathfinder CR Manual - Manual (Page 30)

DMX Distribution System Page 30
DMXPathfinder - Hardware
SECTION 3 -- DMXPathfinder HARDWARE
3.1 THEORY OF OPERATION
Please refer to the Schematic Diagrams in Section 3.3 for assistance in following
this discussion. The first schematic diagram, DMS SYSTEM SIGNAL FLOW, and
Figure 3-1 on the following page, will be the subject of the initial discussion.
The signal flow diagram shows the four main modular components of the Digital
Matrix Switcher, or DMXPathfinder. At left is the Input Module (one of up to 8 in the
system), where DMX source signals arrive at the DMXPathfinder. Next is the
Master Control Module, which receives the signals from the Input Modules and
buffers them for transmission over a twisted-pair bus to the Frame Control Module.
From the Frame Control Module, signals are distributed to the Output Module (one
of 8 per frame), where they are repeated and sent out to the various DMX receiving
devices.
Note that the diagram shows the send, or transmitted direction of signal flow from
left to right. A similar data path exists where return signals are passed in the
opposite direction, and this is shown from right to left.
A more complete description of the specific features and function of each of these
modules will follow.
Figure 3-1 shows a simplified schematic representation of how input/output
matrixing is accomplished in the DMXPathfinder. For the sake of clarity, only the
transmit (send) direction of data flow is shown, and the Master Control and Frame
Control Modules are not shown. Four input line receivers are on the left, from
where signals are optically isolated before passing through a crosspoint matrix
device onto the system I/O bus. Note that in the CBC Halifax system, the system's
8 inputs default to the first 8 of 16 bus channels in a one-to-one relationship. Only in
systems with more than 16 inputs would it be necessary to use the matrix
capabilities of the Input Modules.
The system I/O bus is distributed to every output frame, and in turn to each Output
Module. The crosspoint matrix on each Output Module determines which of the 16