Month: January 2026

05701-A-0284  Honeywell  Catalytic Sensor Drive

Description

The Honeywell 05701-to-0284 is a Catalytic Sensor Drive module used in various Honeywell gas detection systems. This component is critical for powering and controlling catalytic sensors, which detect combustible gases such as methane, propane, and butane.

Key Specifications and Features:

Compatibility: Designed for use with Honeywell’s 5701 series gas detectors.

Function: Provides power and control signals to catalytic sensors.

Reliability: Engineered to perform reliably in harsh environments.

Easy Installation: Simple plug-and-play setup ensures quick integration.

Separately Powered Detectors

Separately powered detectors (e.g. most IR, UV/IR Flame detectors) require three or four

wire connections. The detector documentation will indicate the 0V and +24V power

connections and the positive and negative loop connections. When using flame detectors it

is common practice to use only one detector per loop input.

At the System 57 end of the field cables the two detector signal wires should be connected

to the appropriate channels IN+ and IN- terminals of the Hex Relay Interface Card that is

attached to the required 5704F Control Card. The loop current always flows from the IN+

terminal and returns via the IN- terminal.

The power for the detector may be sourced from the System 57 power supply or a separate

field supply, whichever is most appropriate. In small systems, power can be obtained from

terminals 35 and 36 of the Hex Relay Interface Card, but care must be taken not to exceed

the maximum backplane current loading of 8A. A separate dc power distribution block is

recommended.

For fault monitoring purposes, an end of line (EOL) resistor must be fitted in or after the last

detector on the loop. The typical value for end of line resistance is 5.1k ohms.

The detector cable screen, or steel wire armour or braid as appropriate, should be

connected to the system protective earth. This can be achieved where the cable enters the

screen

cabinet by using a metal cable gland, or by other suitable means, and avoiding any

tails within the cabinet.

Where the cable consists of a separate screen sheath and wire armour or braid, the armour

should be connected at

the cabinet entry to the protective earth and the screen sheath

should be connected to the GROUND terminal of the Hex Relay Interface Card or to a

suitable instrument earth point.

Typical Loop Powered Detector Connections

Loop powered detectors (e.g. most smoke, heat and manual call points) have two wire

connection. The detector documentation will indicate the positive and negative loop

connections. Multiple detectors may be connected in parallel on a single loop input provided

the loop operational limit for quiescent current is not exceeded.

At the System 57 end of the field cables, the two detector wires should be connected to the

appropriate channels IN+ and IN- terminals of the Hex Relay Interface Card that is attached

to the required 5704F Control Card. The loop current always flows from the IN+ terminal and

returns via the IN- terminal.

For fault monitoring purposes an end of line (EOL) resistor must be fitted in or after the last

detector on the loop. The typical value for end of line resistance is 5.1k ohms.

The detector cable screen, or steel wire armour or braid as appropriate, should be

connected to the system protective earth. This can be achieved where the cable enters the

cabinet by using a metal cable gland, or by other suitable means, and avoiding any screen

tails within the cabinet. Where the cable consists of a separate screen sheath and wire

armour or braid, the armour should be connected at the cabinet entry to the protective earth

and the screen sheath should be connected to the GROUND terminal of the Hex Relay

Interface Card or to a suitable instrument earth point.

Typical Loop Powered Detector with IS Barrier Connections

Loop powered intrinsically safe detectors (e.g. most smoke, heat and manual call points)

have two wire connection. The detector documentation will indicate the positive and negative

loop connections. Multiple detectors may be connected in parallel on a single loop input

provided the IS criteria and loop operational limit for quiescent current are not exceeded.

In the safe area, the two wires from the detector should be connected to the field (hazardous

area) side of the barrier. The input (safe area) side wires from the barrier should be

connected to the appropriate channels IN+ and IN- terminals of the Hex Relay Interface

Card that is attached to the required 5704F Control Card. The loop current always flows from

the IN+ terminal and returns via the IN- terminal. The barrier must be earthed appropriately.

For fault monitoring purposes an end of line (EOL) resistor must be fitted in or after the last

detector on the loop. The typical value for end of line resistance is 5.1k ohms.

When using an external barrier the IS compatibility link for the input must be set

appropriately. Intrinsically safe systems must be earthed at one point only. All detector cable

screens should be connected separately to the IS safety ground.

Honeywell O5701-A-0351 is a gas detector Control Card for industrial safety monitoring systems, belonging to the highly regarded Signalpoint or System 57 control system series.

This component is very common in petroleum, chemical and semiconductor factories, mainly used to receive signals from remote sensors and drive alarm devices.

Core parameters and functions of the product

Full model name: Honeywell O5701-A-0351 (abbreviated as 5701 Control Module in some documents)

Type: Single Channel Control Card.

Input signal: * Receives 4-20mA standard industrial signals from gas detectors (such as catalytic combustion type, electrochemical type or infrared detector).

It can also support mV bridge circuit signals (for certain specific catalytic combustion probes).

The display interface: The front of the module is equipped with a 3-digit digital liquid crystal display (LCD), which can display the gas concentration, fault code and alarm status in real time.

Output control: It is equipped with multi-level relay output (typically: low alarm A1. high alarm A2. Fault), which is used to interlock sound and light alarms or shut-off valves.

1. Physical Structure and panel description

This card adopts a plug-and-pull design and is usually installed in a 5701 Rack.

LED indicator light

AL1/AL2 (red) : Concentration exceeds the set threshold.

Fault (yellow) : Detector disconnection, short circuit or internal fault of the module.

Inh (amber) : Maintains the inhibited state (Inhibit).

Key operation: There are usually hidden keys at the bottom of the panel, which are used to Reset the alarm or enter the menu for zero point/range calibration.

2. Core technical features

Flexibility: Supports software programming and setting of parameters such as alarm points, lag amounts, and delay times.

Stability: Industrial-grade isolation design, strong resistance to electromagnetic interference (EMC).

Compatibility: It is compatible with Sensepoint, Searchline Excel under Honeywell and most third-party 4-20mA transmitters.

3. Common Application Scenarios

Combustible gas monitoring: Monitoring the leakage of methane, hydrogen or liquefied gas in the environment.

Toxic gas monitoring: Monitor low-concentration toxic gases such as carbon monoxide and hydrogen sulfide.

Hypoxia monitoring: Online monitoring of oxygen concentration in industrial sites.

5704 Gas Card and Catalytic Type Detector

Catalytic detectors require a three wire connection and the detector documentation will

indicate three connections S, 01 and NS, which are usually brown, white and blue

respectively.   At the System 57 end of the field cable, the three detector wires should each be

connected to the respective matching S, 01 or NS terminal of the appropriate channel on the

Quad Relay Interface Card that is attached to the required Four Channel Control Card.

5704 Gas Card and 2 Wire Loop Powered Detectors

Loop powered detectors require a two wire connection and the documentation will indicate

the positive and negative loop connections, usually brown and blue respectively.

At the System 57 end of the field cable the two detector wires should be connected to the S

(positive) and 01 (negative) terminals of the appropriate channel on the Quad Relay

Interface Card that is attached to the required Four Channel Control Card.

5704 Gas Card and 3 Wire 4-20mA Transmitter

ctor documentation

Transmitters require either three or four wire connections and the dete

will indicate the 0V and +24V power connections and the positive and negative loop

connections. At the System 57 end of the field cable the detector loop signal wires sh

connected to the S, 01. NS terminals on the Quad Relay Interface Card that is attached to

the required Four Channel Control Card. The exact terminals used vary depending upon

whether three or four wire topology is used, the requirement for a loop current source

configuration and the channel to be connected to. The transmitter power connection +2

and 0V should be connected to a suitable dc supply.

ould be

4V

ote: Terminals 35 and 36 on the Relay Interface Card are input terminals only and cannot

N

be used to power the transmitter.

he Schematic below details the connections for 3 wire current source transmitters. For

T

other schematics (including isolated and barrier) refer to operating manual 05704-M-5001

5704 Fire Card

The 5704F fire input circuit operates from the system dc input supply (21 to 32V) but has a

built-in voltage limiter that limits the maximum loop voltage to +24V to protect the detectors

from damage. When the system supply is less than +24V the limiter has no effect and the

loop will see the true input supply voltage. The loop current is determined by measuring the

voltage across a 220 ohm current sense resistance. A link selectable 330 ohm barrier

equivalent resistance is incorporated for use when an external IS barrier is NOT fitted. For

fault monitoring purposes, an end of line (EOL) resistor must be fitted in or after the last

detector on the loop. The typical value for the end of line resistance is 5.1k ohms although

this may need to be reduced when many detectors are fitted onto the loop.

An equivalent circuit of one fire input together with an example detector connection is shown

below:-

Line Resistance

Detectors should be located such that the line resistance of the cable required does not

prevent correct operation. As a general guide and for a typical installation of twenty low

quiescent current detectors, the loop cable resistance should be kept below 100 ohms total

(50 ohms per core). The table below gives a quick guide to the maximum cable lengths

permitted in this case:

Interface Card Connections

System 57 interface cards use a common card with differing numbers of terminal blocks

fitted according to which type of card it is. The picture below illustrates a card with the

maximum number of terminals fitted. The tables show the terminal connections for 5701.

5704 gas and 5704 fire interface cards.

8 Detector Connections

The following sections show generic installation schematics for the most common types of

fire or gas detector and System 57.

8.1 Cable Earthing/Grounding

The detector cable screen or steel wire armour (or braid), as appropriate, should be

connected to the system (protective) earth. This can be achieved where the cable enters the

cabinet by using a metal cable gland, or by other suitable means, and avoiding any screen

‘tails’ within the cabinet.

Where the cable consists of a separate screen sheath and wire armour (or braid), the

armour should be connected, at the cabinet entry, to the protective earth and the screen

sheath should be connected to the GROUND terminal of the Field Interface/Relay Card or to

a suitable instrument earth point.

Note: Where a detector is earthed locally, either to the Earth Stud or through the detector

casing or mounting, to avoid earth loops the screen sheath of the cable should only be

connected at one end, i.e., at the detector or at the Interface/Relay Card.

8.2 5701 Gas Card and Catalytic Type Detector

Catalytic detectors require a three wire connection and the detector documentation will

indicate three connections S, 01 and NS, which are usually brown, white and blue

respectively. At the System 57 end of the field cable, the three detector wires should each be

connected to the respective matching S, 01 or NS terminal on the Field Interface or Relay

Card that is attached to the required Single Channel Display Card.

5701 Gas Card and 2 Wire Loop Powered Detectors

Loop powered detectors require a two wire connection and the detector documentation will

indicate the positive and negative loop connections, usually brown and blue respectively.

At the System 57 end of the field cable the two detector wires should each be connected to

one of either the S, 01 or NS terminals on the Field Interface or Relay Card that is attached

to the required Single Channel Display Card. The two terminals used will vary depending

upon whether the location of the measuring resistance is in the loop supply or return paths.

Transmitters powered from the 5701 Control Card require either three or four wire

connections and the detector documentation will indicate the 0V and +24V power

connections and the positive and negative loop connections.

At the System 57 end of the field cable the detector wires should be connected to the S, 01.

NS, 0V or 24V terminals on the Field Interface or Relay Card that is attached to the required

Single Channel Display Card. The exact terminals used vary depending upon whether three

or four wire topology is used, and the requirement for loop current source or sink

configuration. The Schematics below detail the connections for 3 wire current sink or source

transmitters. For other schematics (including isolated and barrier) refer to operating manual

05701-M-5001.