Innotech Genesis II Digital Controller (v5) - Manual (Page 105)

Page 105
Genesis II Installation Instructions
© Mass Electronics Pty Ltd 2010 Chapter 5 – Network Installation
Any cable that meets or exceeds all the stated specifications is suitable for use:
• 2 twisted pairs
• Minimum conductor cross section AWG24 (0.205 mm 2 )
• Stranded core type is recommended (7 strands of 0.193 mm)
• Conductor Foil screened cable with a wire drain
• Less than 50 pf capacitance per metre between conductors
• Less than 80 pf capacitance per metre between conductors and screen
• Impedance 100 – 120 Ohms
• Sheath thickness 0.8 mm 240 V rated
• Equivalent to the Belden Part #8102
5-3.3 Wiring Topology
Installation of Primary devices on a Genesis Network must adhere to the Bus topology. A Bus
Topology is produced by connecting from one device to the next and then onto the next. Refer to
Figure 5-1 below.
A simple means to identify if bus topology is used is to check that:
• There are TWO end connections
• Any joining is made between TWO cable ends only
Furthermore, there are a number of rules which apply to the comms connection of a Primary
Network:
1. The screen must be continuous.
2. Only one point earthed on the screen.
3. Even if a network has a device with a soft earth, one hard earth is still required on that network.
4. The Net and Global networks should have the same length cable run and path.
5. If a repeater is installed, each side of that repeater is a separate network and each requires a
bonded earth connection on the screen.
6. Using isolated devices, devices with isolated comms cards or using an isolated MPI does not
alter any of these rules.
7. There are no End of Line termination (EOL) requirements on the primary network.
Bus Topology Bus Topology
CORRECT
Star Topology Star Topology Ring Topology
WRONG
Figure 5-1: Correct and Incorrect Bus Topology