GE Industrial Solutions HE300GEN251 - Manual (Page 28)

CH. 4: GENIUS 23 SEP 1999 PAGE 29
CHAPTER 4: GENIUS COMMUNICATIONS
This chapter is just a brief overview and introduction to the Genius network. It does not cover detailed
information on the Serial Bus Option card or the AV-300i drives.
4.1 Introduction to Genius
Genius is a high speed token passing network which has been used in industrial applications for many
years. The network supports up to 32 devices, with baud rates of up to 153.6kbaud. A wide variety of
Genius devices exist which can reside on the network, ranging from intelligent I/O blocks to more
sophisticated communications devices such as personal computers. In recent years a number of third
party devices have emerged, including Operator Interface Units, valve manifolds, RF tag readers, etc.
In a typical industrial application, Genius devices are distributed throughout a fairly wide area, wired in a
daisy chained fashion with a single shielded, twisted pair. The Serial Bus Interface Genius option card
allows the AV300/DV300 Drives to be distributed on the factory floor on the same twisted pair as the I/O
blocks and other Genius devices. This provides a new level of PLC integration for the drives. The
physical nature of the network can allow for great savings in wiring, as many discrete wires can be
replaced with a single communications cable. This allows tasks such as starting, stopping, reversing, and
changing speeds to be accomplished over the LAN. In addition, drive parameters and
diagnostic data
previously not available to the PLC are easily accessible.
Figure 4.1. Typical Genius Devices and Architecture
4.2 Network Architecture
Normally, a GE Fanuc programmable controller runs the network, through a PLC module called a Genius
Bus Controller (GBC). Devices (up to 32 in number) are wired in a daisy chained fashion. Network
devices support four communications terminals, Serial 1, Serial 2, Shield In and Shield Out. The network
is terminated at each end with an appropriate terminating resistor. The value of the resistor should be
chosen to match the characteristic impedance of the cable. Refer to GE Fanuc Automation publication
GFK-90486 for help in selecting an appropriate cable type for your application. Note: If the characteristic
impedance of the cable is unknown, 120 ohm terminating resistors should be used.