Specifications

Table Of Contents

SkyePlus™ MXH and MXU Multiplexer Reference Guide

Appendix B

Using Multiple SkyePlus Multiplexers

Overview

With SkyeTek Protocol v3, you can operate more than one SkyePlus multiplexer,

although there are limitations due to:

● GPIO control lines

● Performance issues related to signal loss and delay

GPIO Control Lines

Each eight-port multiplexer requires three general purpose I/O (GPIO) lines to

address all eight ports. The Mounting Hole (MH) style readers have four GPIO

lines available, and the Compact Flash (CF) style readers have six GPIO lines.

(Refer to the pin mapping information in your SkyeModule reader’s reference

guide for more specific pin information.)

This means the MH-style reader can operate one SkyePlus multiplexer and the

CF-style readers can operate two. (Alternatively, you can operate a four-port

multiplexers with only two I/O lines, although SkyeModule readers do not by

default support this configuration. Contact SkyeTek for assistance if you wish to

use this model for your application.)

Signal Loss

For the MXU at a typical frequency of 900 MHz, the loss through one mux is

approximately 1.3dB. Cabling losses can account for an additional few tenths of

a decibel. With two multiplexers and cabling to connect them, there could be

close to 3 dB (½ power) in loss.

For the MXH at 13.56 MHz, the analysis is similar although signal loss will be

slightly less.