Detcon FP-624D - Manual (Page 7)

Model FP-624D
FP-624D Instruction Manual Rev. 1.2 Page 3 of 42
Figure 4 Response Curves
1.2 Modular Mechanical Design
The Model FP-624D Sensor Assembly is completely modular and is made up of four parts:
1) FP-624D Plug-in Transmitter
2) Field Replaceable Combustible Gas Sensor
3) Connector PCB
4) Splash Guard
FP-624D Plug-in Transmitter
The Plug-in Transmitter Module is a microprocessor-based package that plugs into the connector board located
in the explosion proof junction box. Circuit functions include extensive I/O circuit protection, sensor pre-
amplifier, sensor temperature control, on-board power supplies, microprocessor, LED display, magnetic
programming switches, a linear 4-20mA DC output, and a Modbus RTU output. Magnetic program switches
located above and below the LED Display are activated via a hand-held magnetic programming tool, thus
allowing non-intrusive operator interface with the Transmitter Module.
Calibration can be accomplished
without declassifying the area. Electrical classifications are Class I, Division 1, Groups B C D.
Figure 5 Circuit Functional Block Diagram
I/O
Circuit
Protection
RS-485
4-20mA
Display
Micro-
Processor
Temperature
Control
Pre-Amp Analog 4-20mA Out
Power In
Power Supply
Plug-In
Sensor
Element
Modbus RTU
Relays Out