Specifications

Smeal Pumper Demo # 4276
Page 49 of 58
charging system. No add-on modules shall be acceptable; the module with the outputs must
perform this function.
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3. Output Device: The System shall have solid-state output devices. Each solid-state output shall be
a MOS-FET (Metal Oxide Semiconductor - Field Effect Transistors); MOS-FETs are solid-state
devices with no moving parts to wear out. A typical relay when loaded to spec has a life of
100,000 cycles. The life of a FET is more than 100 times that of a relay. No add-on modules shall
be acceptable; the module with the outputs must perform this function.
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4. Flashing Outputs: The System shall be able to flash any output in either A or B phase, and logic
is used to shut down needed outputs in park, or any one of several combined interlocks. The
flash rate can be selected at either 80, or 160 FPM. This means any light can be specified with a
multiplex truck with no need to add flashers. Flashing outputs can also be used to warn of
problems. No add-on modules shall be acceptable; the module with the outputs must perform this
function.
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5. PWM: The modules shall have the ability to PWM at some outputs so that a Headlight PWM
module is not needed. No add-on modules shall be acceptable; the module with the outputs must
perform this function.
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6. Diagnostics: An output shall be able to detect either a short or open circuit. 
Inputs:
1. The inputs shall have the ability to switch by a ground or battery signal.
2. The inputs shall be filtered for noise suppression via hardware and software so that RF or dirty
power will not trick an input into changing its status.
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System Network:
The Multiplex system shall contain a Peer-to-Peer network. A Master Slave Type network is not suitable
for the Fire/Rescue industry. A Peer-to-Peer network means that all the modules are equal on the
network; a Master is not needed to tell other nodes when to talk.
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System Reliability:
The Multiplex system shall be able to perform in extreme temperature conditions, from -40° to +85° C (-
40° to +185° F.) The system shall be sealed against the environment, moisture, humidity, salt or fluids
such as diesel fuel, motor oil or brake fluid. The enclosures shall be rugged to withstand being mounted in
various locations or compartments around the vehicle. The modules shall be protected from over voltage
and reverse polarity.
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WEATHERPROOF DOOR SWITCHES
Due the harsh environment and susceptibility to moisture on the fire ground, the fire apparatus
compartment doors shall utilize weatherproof switches. Two different types of switches shall be used.
Weatherproof proximity switches shall be utilized where space permits. In tight locations, mechanical
weatherproof switches shall be used. No Exceptions. The switches shall be used for activation of the
compartment lights and to provide a signal to the door open circuit in the cab.
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ELECTRICAL TERMINALS