Triconex 3805H Safety Analog Output Module Unit

Module Feature

3805H belongs to Triconex Tricon series safety I/O module, triple modular redundant TMR design.

It provides 8 channels of DC coupled 4~20mA analog output, 12-bit resolution, output accuracy less than 0.25% FSR. It supports hot swap during system running, each channel has overvoltage and reverse polarity protection. It receives control command from main processor via backplane tri-bus, performs voting logic to ensure fault tolerant output. Certified SIL3 by TÜV, it sends analog setpoint signals to valve positioners, variable speed drives and control valves in safety instrumented system.

Working principle

Three independent internal circuits receive the same digital command from Tricon main controller.

After hardware voting, the module converts the digital value into stable 4-20mA current signal and transmits it to field control equipment. If one channel fails, the remaining two healthy channels can maintain normal output without safety trip. The module continuously monitors loop open circuit, short circuit and internal hardware fault, and uploads fault alarm to SIS host.

Onboard components

Three redundant signal conversion boards, DAC conversion chip group, TMR voting logic circuit, backplane tri-bus interface, surge protection circuit, channel status indicator array, edge connector and terminal matching assembly.

LED indicators

Front LEDs indicate module healthy, channel active, fault alarm and backplane bus communication status.

Hardware self‑diagnosis

Built-in supervision detects loop open, loop short, output over-range, internal leg mismatch, backplane communication loss and power anomaly. Fault records can be viewed through Triconex Trident and TriStation software.

Programming software

TriStation 1131, used for channel configuration, output range setup, safety logic programming and fault log reading.

Electrical & Process Parameters

Model:3805H Brand:Triconex (Invensys / Schneider) Device type:TMR safety analog output module Function:4-20mA analog control output for SIS safety interlock system

Mechanical & Structure

Mounting:Plug-in slot installation inside Tricon rack Protection class:IP20 Housing:Metal reinforced industrial module housing

Environmental

Operating temperature:0℃ ~ +60℃ Storage temperature:-40℃ ~ +85℃ Ambient humidity:5~95% non‑condensing

Certification:SIL3, TÜV, CE

Status:Original Triconex SIS spare

Installation

Confirm rack power normal, insert module into designated slot and lock fixing screws.

Wire field actuators and positioners to matched terminal board, download I/O configuration and perform loop signal test before commissioning.

Interface

Tricon tri-bus backplane connector, 4-20mA analog output terminal block, 24VDC auxiliary power terminal.

Diagnostic

Channel fault alarm: Field wire open/short, actuator loop power abnormal or channel circuit failure. Output drift: Loop load out of specification, ground interference or internal DAC aging. Module fault: TMR leg mismatch, backplane bus interruption or module power failure.

Product Brief

Triconex 3805H analog output module, 8-channel TMR SIL3 AO spare for chemical and oil & gas SIS safety interlock cabinet replacement.