User's Manual

E2 Wireless I/O Page 13

The power supply input and battery charging are hosted on a 4-way terminal on the

bottom edge of the module labeled “Power Supply”.

To allow increased I/O Capacity, a second 4-way terminal labeled “Expansion I/O”

provides a +12 Volt supply and RS485 communications for any 115S serial expansion

I/O modules.

Up to three 115S-11, one 115S-12, or one 115S-13 may be powered by the Expansion

I/O Power Connection

The onboard power supply provides up to 1 Amp for battery charging, and up to 1 Amp

to supply I/O modules.

2.3 Radio

The following radio variants are available in the E2 dependent on the country of

operation.

900 MHz Spread Spectrum radio

The radio operates in the 902-928 MHz ISM band and uses frequency hopped spread

spectrum modulation, which is a method of transmitting radio signals by rapidly

switching the carrier among many frequency channels, using a pseudorandom

sequence known to both transmitter and receiver.

There are eight different pseudo random sequences known as “Hops sets”. Each Hop

set uses 50 channels and steps through these channels after every transmission.

The receiver is continually scanning all 50 channels and when a valid data packet is

heard it locks on to the channel and receives the data.

A spread-spectrum transmission offers some advantages over a fixed-frequency

transmission. These are - Spread-spectrum signals are more resistant to narrowband

interference, they are difficult to intercept or eavesdropper because of the

pseudorandom transmission sequences and transmissions can share a frequency band

with other types of conventional transmissions with minimal interference.

E2 Expansion

I/O

115S- XX