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Limit Switch Box (Switchmaster) for Pneumatically Automated Valves

Reliable Position Feedback for Industrial Applications

The limit switch box, also known as Switchmaster, provides precise electrical position feedback for automated valves. Mounted directly onto pneumatic actuators according to VDI/VDE 3845 (Namur interface), it reliably signals the end positions “open” and “closed.” The available models are designed for continuous industrial operation and are offered in mechanical or inductive versions. Optional features include visual position indicators and pre-configured terminal connections.

Pre-Assembled Automated Valves with Pneumatic Actuator, Namur Valve and Switch Box

We supply ready-made automated valve assemblies including pneumatic actuatorNamur solenoid valve and limit switch box – fully assembled and tested. Butterfly valves with limit switch box are particularly valued for their compact design and suitability for industrial pipeline systems. Ball valves with limit switch box are carefully configured: torque calculation, professional actuator mounting and precise adjustment of the switchmaster ensure reliable position feedback and long service life.

Each automated unit is tested prior to delivery, providing a ready-to-install solution that reduces installation time and ensures maximum operational safety.

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Limit switch box for valves – position feedback with mechanical and inductive sensors for industrial automation
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9 item (s) of 9
Switchmaster-M2 Mechanical Microswitch 4V/DC-250V/AC 1mA - 5A IP67 Limit Switch
Product number
Copy to clipboard 710-1050
Mechanical position indicator OPEN/CLOSED, 0...90° swivel angle, switching function change-over contact, voltage range 4V/DC-250V/AC, current range 1mA - 5A, contacts gold-plated, plastic housing (Lexan 143), antistatic coating, protection class  IP67, temperature range -20°C to +70°C
Typ:
Mechanischer Positionsrückmelder AUF/ZU
Switching function:
Wechsler
Spannungsbereich:
4V/DC-250V/AC
Protection class :
IP67
Price €79.55
€94.66 incl. VAT
Delivery Time: in stock
Available: In Stock
Switchmaster-N2 Inductive sensor Namur EN 60947-5-6 Explosion-proof ATEX limit switch
Product number
Copy to clipboard 710-1052
Inductive sensor OPEN/CLOSE  Namur EN 60947-5-6, explosion-proof Ex ia IIB T6, 0...90° swivel angle, switching function in end position damped or undamped, switching capacity max. 34 mW, nominal voltage 8 V/DC, max. 16V/ DC, output current damped <1 mA, undamped >3 mA, plastic housing (Lexan 143), antistatic coating, degree of protection IP67, temperature range: -20°C to +70°C, ATEX marking: II 2 G Ex ia IIB T6
Switching function:
plus schaltend, PNP Schließer, in Endlage bedämpft oder unbedämpft
Typ:
Induktiver Sensor AUF/ZU
Spannungsbereich:
10 - 30V/DC
Protection class :
IP67
Price €220.00
€261.80 incl. VAT
Delivery Time: in stock
Available: In Stock
Switchmaster-D2 Inductive sensor 10 - 30V/DC IP67 Limit switch
Product number
Copy to clipboard 710-1051
Inductive sensor OPEN/CLOSED, 0...90° swivel angle, switching function plus switching, PNP NO contact, in end position damped or undamped, voltage range 10 - 30V/DC, current range 100 mA, housing plastic (Lexan 143), antistatic coated, protection class IP67, temperature range: -20°C to +70°C
Switching function:
plus schaltend, PNP Schließer, in Endlage bedämpft oder unbedämpft
Typ:
Induktiver Sensor AUF/ZU
Spannungsbereich:
10 - 30V/DC
Protection class :
IP67
Price €160.00
€190.40 incl. VAT
Delivery Time: in stock
Available: In Stock
Limit switch box EB300-PP2I02
Product number
Copy to clipboard 711-PP2I02
Limit switch box EB300-PP2I02 with inductive switchesFlexible box made of polyamide with polycarbonate cover, Mounting bracket and shaft made of polyamid, 2x inductive proximity switches P+F, NBB2-V3-E2 (PNP N.O.), LED Indicator, Max. current: 0-100mA with protection IP67
Switching function:
2x inductive proximity switches P+F, NBB2-V3-E2 (PNP N.O.)
Voltage :
10-30 V DC
Body:
Polyamide (PA6)
Protection class :
IP67
Price €109.60
€130.42 incl. VAT
Delivery Time: in stock
Available: In Stock
Limit switch box EB300-PP2M02
Product number
Copy to clipboard 711-PP2M02
 Limit switch box EB300-PP2M02 with mechnical micro switchesFlexible box made of polyamide with polycarbonate cover, Mounting bracket and shaft made of polyamide, Voltage: 12-250 V AC/DC, Operating current: 0,1-10A with protection IP67
Switching function:
Mechanical micro switches Cherry, D44X (SPDT, NO/NC)
Voltage :
12-250 V AC/DC
Body:
Polyamide (PA6)
Protection class :
IP67
Price €55.02
€65.47 incl. VAT
Delivery Time: in stock
Available: In Stock
Limit switch box EB300-PE2M02
Product number
Copy to clipboard 711-PE2M02
 Limit switch box EB300-PE2M02 with mechnical micro switchesFlexible box made of polyamide with polycarbonate cover, Mounting bracket and shaft made of stainless steel, Voltage: 12-250 V AC/DC, Operating current: 0,1-10A with protection IP67
Switching function:
Mechanical micro switches Cherry, D44X (SPDT, NO/NC)
Voltage :
12-250 V AC/DC
Body:
Polyamide (PA6)
Protection class :
IP67
Price €100.24
€119.29 incl. VAT
Delivery Time: in stock
Available: In Stock
Limit switch box EB300-PE2I02-7
Product number
Copy to clipboard 711-PE2I02-7
 Limit switch box EB300-PE2I02-7 with inductive switchesFlexible box made of polyamide with polycarbonate cover, Mounting bracket and shaft made of stainless steel, Voltage: 10-30 V DC, Operating current: 0-200mA with protection IP67 and yellow LED indicator
Switching function:
Induktive Näherungsschalter IFM, IS5001, 3-Draht PNP
Voltage :
10-30 V DC
Body:
Polyamide (PA6)
Protection class :
IP67
Price €152.69
€181.70 incl. VAT
Delivery Time: in stock
Available: In Stock
Limit switch box EB300-VP2M02-551-ED ATEX
Product number
Copy to clipboard 711-VP2M02-551-ED
Limit switch box EB300-VP2M02-551-ED with mechanical switches for Ex ZoneFlexible and conductive vestamide box, Mounting bracket and shaft made of polyamide, 2x mechanical Ex d switches Bartec 07-1511-1030, 3-wire NO/NC for Ex zone 1+2 and 21+22, protection IP66 with Silver contact and many other options
Switching function:
2x mechanical Ex d switches Bartec 07-1511-1030, 3-wire NO/NC
Voltage :
24V DC / 250V AC
Body:
Vestamide
ATEX:
II 2G Ex de IIC T6 Gb und II 2D Ex t IIIC T80°C Db
Protection class :
IP66
Price €172.52
€205.30 incl. VAT
Delivery Time: in stock
Available: In Stock
Limit switch box EB300-VP2S02-IA ATEX
Product number
Copy to clipboard 711-VP2S02-IA
Limit switch box EB300-VP2M02-551-ED with inductive sensors for Ex ZoneFlexible and conductive vestamide box, Mounting bracket and shaft made of polyamide, 2x inductive slot type sensors P+F, SJ3,5-N, 2-wire Ex ia for Ex zone 1 and 21, protection IP67 with many other options
Switching function:
2x inductive slot type sensors P+F, SJ3,5-N, 2-wire Ex ia
Voltage :
8V DC
Body:
Vestamide
ATEX:
II 2G Ex ia IIC T6 Gb und II 2D Ex ia IIIC T80°C Db
Protection class :
IP67
Price €188.86
€224.74 incl. VAT
Delivery Time: in stock
Available: In Stock

Frequently Asked Questions – Limit Switch Box (Switchmaster)

A limit switch box (also known as a position feedback unit, valve monitor, or – under the FERGO brand name – Switchmaster) is a device mounted on a pneumatic part-turn actuator or electric part-turn actuator that detects the actual position of the process valve (OPEN / CLOSED) and reports it electrically to the control system (PLC/DCS/control room):
  • Visual position indicator: The unique Switchmaster design makes the valve position (OPEN/CLOSED) clearly visible from a distance – without any current measurement or screen
  • Electrical feedback to PLC/DCS: Switch contacts (mechanical or inductive) signal the control system precisely when the valve has reached the end positions "fully open" and "fully closed" – essential for automated process sequences, interlocks, and alarm functions
  • Rotation angle: 0° to 90° – matching all quarter-turn actuators for ball valves, butterfly valves, knife gate valves, and plug valves
  • Mounting: Directly on the NAMUR hole pattern of the actuator or the side flange; no additional brackets or adapters required
  • Adjustability: Switching points and sensitivity are field-adjustable to compensate for different actuator geometries and mechanical tolerances
The limit switch box closes the control loop in valve automation: the NAMUR solenoid valve sends the positioning command; the limit switch box confirms that the valve has actually reached the desired end position.
The three Switchmaster core models differ in sensor type, voltage range, wear behaviour, and suitability for hazardous areas:

Switchmaster M2 – Mechanical microswitch (standard, non-ATEX):
  • Sensor: Mechanical microswitch; switching function: change-over contact (NO + NC simultaneously) – maximum wiring flexibility with a single switch element
  • Voltage range: 4V DC – 250V AC; current range: 1mA – 5A; gold-plated contacts (corrosion-resistant; reliable at milliamp signal levels)
  • Protection: IP67; housing: Lexan 143 plastic, antistatic coating; temperature: −20°C to +70°C
  • Choose M2 when: Standard industrial applications without ATEX requirement; wide voltage compatibility (24V DC to 230V AC); applications needing very low control currents (from 1mA) or higher load currents (up to 5A); wherever a change-over contact is needed for both NO and NC wiring without rewiring
Switchmaster D2 – Inductive sensor PNP (standard, non-ATEX):
  • Sensor: Inductive proximity switch; switching function: PNP NO contact; contactless operation – no mechanical wear
  • Voltage range: 10–30V DC; current: max. 100mA; switching function: damped or undamped in end position
  • Protection: IP67; housing: Lexan 143, antistatic; temperature: −20°C to +70°C
  • Choose D2 when: 24V DC PLC-controlled plant (PNP outputs); high switching frequency; wet or vibrating environments where mechanical contacts would wear; no ATEX requirement and 24V DC available
Switchmaster N2 – Inductive NAMUR sensor (ATEX, Ex ia):
  • Sensor: Inductive sensor per NAMUR EN 60947-5-6; 2-wire; damped/undamped in end position
  • Nominal voltage: 8V DC (max. 16V DC); output current: damped <1mA, undamped >3mA; max. switching capacity: 34mW
  • Protection: IP67; housing: Lexan 143; temperature: −20°C to +70°C
  • ATEX marking: II 2 G Ex ia IIB T6 → Zone 1 (gas) and Zone 21 (dust); supply from certified intrinsically safe circuit (Zener barrier or galvanic isolator)
  • Choose N2 when: ATEX Zone 1, Zone 2, Zone 21, or Zone 22; plant with NAMUR-compatible evaluation units (barriers/isolators); where intrinsically safe circuits are required by the area classification
The EB300 series is a modular, flexible limit switch box in polyamide (PA6) with polycarbonate cover or conductive vestamide housing for ATEX applications. Unlike the Switchmaster SM housing (Lexan 143), the EB300 has an interchangeable mounting bracket, shaft, and sensor configuration:

EB300-PP2M02 – Mechanical microswitches, standard:
  • 2× Cherry mechanical microswitches; PA6 housing + PC cover; polyamide bracket and shaft; 12–250V AC/DC; IP67
  • Use: Standard industrial environments without ATEX; wide voltage range
EB300-PP2I02 – Inductive proximity switches, standard:
  • 2× Pepperl+Fuchs NBB2-V3-E2 inductive PNP NO; yellow LED indicator; PA6 + PC cover; polyamide bracket and shaft; max. 100mA; IP67
  • Use: 24V DC PLC plants; contactless position detection
EB300-PE2M02 – Mechanical microswitches, stainless steel bracket:
  • 2× Cherry mechanical microswitches; PA6 + PC cover; stainless steel mounting bracket and shaft (enhanced corrosion resistance); 0.1–10A; IP67
  • Use: Corrosive environments; offshore; chemical plants; where standard plastic bracket is insufficient
EB300-VP2M02-551-ED – Mechanical ATEX switches Ex d, Zone 1+2/21+22:
  • 2× Bartec 07-1511-1030 mechanical Ex d switches; 3-wire changeover with silver contacts; conductive vestamide housing (electrostatic dissipative); polyamide bracket and shaft; ATEX Zone 1+2 and Zone 21+22; IP66
  • Use: Ex d (flameproof enclosure) for Zone 1 gas + Zone 21 dust; most robust ATEX option
EB300-VP2S02-IA – Inductive ATEX sensors Ex ia, Zone 1+21:
  • 2× Pepperl+Fuchs SJ3,5-N inductive slot sensors; 2-wire Ex ia; conductive vestamide housing; Zone 1 and Zone 21; IP67
  • Use: Intrinsically safe version for Zone 1 / Zone 21; NAMUR-compatible evaluation unit required
Both technologies are proven; the right choice depends on the application:

Mechanical microswitch (SM-M2, EB300-PP2M02, EB300-PE2M02):
  • Advantages:
    • Universal voltage range 4V DC to 250V AC – compatible with virtually any control system without voltage converters
    • Change-over contact (NO + NC simultaneously) – maximum wiring flexibility in a single switch element
    • Very low switching currents (from 1mA) – compatible with electronic PLC inputs with minimal hold current requirements
    • Higher load currents (up to 5A or 10A for PE2M02) – direct motor contactor control without interposing relays
    • Robust and low-maintenance; no external supply voltage required for the sensor itself
  • Disadvantages: Mechanical contact wear; limited switching frequency (typically ≤50 Hz sustained); sensitive to vibration and moisture if inadequately protected
Inductive sensor (SM-D2, SM-N2, EB300-PP2I02, EB300-VP2S02-IA):
  • Advantages:
    • Contactless – no mechanical wear; unlimited theoretical switching frequency
    • Immune to moisture, dust, and vibration (no moving parts in the sensing zone)
    • Fast switching times; precise, repeatable switching points
    • ATEX-capable: NAMUR version (SM-N2, EB300-VP2S02-IA) for Zone 1/21 with intrinsically safe supply; PNP version suitable for Zone 2/22 with appropriate housing
  • Disadvantages: Narrow voltage range (24V DC for PNP; 8V DC for NAMUR); separate supply voltage required for the sensor; no true change-over contact (PNP has NO only; NAMUR is 2-wire with defined current threshold)
Quick guide: Standard control panel, wide voltage range, change-over contact needed → M2 mechanical. 24V DC PLC, high switching frequency, no ATEX → D2 inductive PNP. ATEX Zone 1 or 21, intrinsically safe circuit → N2 NAMUR inductive.
In hazardous areas (ATEX zones) all electrical equipment – including limit switch boxes – must be approved for the relevant zone. FERGO offers several ATEX versions:

Switchmaster N2 – Ex ia IIB T6 (Zone 1 / Zone 21):
  • Protection level: Intrinsic safety (Ex ia) – no ignitable energy under up to two simultaneous faults; highest safety level
  • ATEX marking: II 2 G Ex ia IIB T6; gas group IIB (H₂, ethylene, town gas etc.); temperature class T6 (max. 85°C surface temperature)
  • Supply: Exclusively from a certified intrinsically safe circuit (Zener barrier or galvanic isolator)
  • Suitable for: Zone 1+2 (gas) and Zone 21+22 (dust)
EB300-VP2M02-551-ED – Ex d IIC (Zone 1 / Zone 21):
  • Protection level: Flameproof enclosure (Ex d) – any internal ignition is contained and cannot propagate outside
  • Bartec mechanical switches; conductive vestamide housing; IP66; Zone 1+2 and Zone 21+22
  • Suitable for: Applications where mechanical switch contacts (no external sensor supply) are preferred and Zone 1 is present
EB300-VP2S02-IA – Ex ia (Zone 1 / Zone 21, inductive):
  • P+F inductive slot sensors Ex ia; conductive vestamide housing; 2-wire; IP67
  • Suitable for: Zone 1 and Zone 21 with intrinsically safe circuit; contactless position detection in hazardous areas
Typical applications for ATEX limit switch boxes: Chemical and petrochemical plants; refinery valves; gas pipelines; solvent processing; pharmaceutical and food plants with flammable cleaning agents or dusts; all valves in areas classified under ATEX Directive 2014/34/EU.
Mounting the FERGO limit switch boxes (Switchmaster SM and EB300 series) is standardised and requires minimal tools:

Mounting:
  • The limit switch box mounts directly on the NAMUR hole pattern of the part-turn actuator (VDI/VDE 3845) or on the side flange of the actuator – no external brackets or adapters are required when the actuator has the NAMUR hole pattern (all FERGO actuators do)
  • The actuator output shaft engages the coupling shaft of the limit switch box; the cam discs inside the box rotate with the valve shaft and actuate the switches at the end positions
  • All FERGO actuators carry the NAMUR hole pattern – all Switchmaster models mount directly without special tools
Setting the switching points:
  • Inside the limit switch box are adjustable cam discs (SM series) or adjustable actuating flags (EB300 series) that can be freely positioned within the 0–90° rotation range
  • Commissioning sequence: Drive valve to CLOSED end position → adjust CLOSED cam to trigger → drive valve to OPEN end position → adjust OPEN cam to trigger → verify with PLC feedback
  • The unique visual indicator of the Switchmaster (red/green display bar visible from a distance) gives immediate optical position confirmation during commissioning, before the PLC wiring is complete
Electrical connection: Cable entry via M20×1.5 cable gland; terminals inside for conductors up to 2.5mm²; DIN plug option available for quick field replacement.
The limit switch box provides electrical output signals compatible with standard PLC input cards, with the signal type depending on the model:

SM-M2 (mechanical, change-over):
  • 2 switches for OPEN end position and 2 switches for CLOSED end position; each switch provides NO + NC (change-over) → 4 freely wirable contacts total
  • Typical PLC wiring: NO contact → PLC input "valve OPEN confirmed" / "valve CLOSED confirmed"; NC contact → PLC input for alarm "end position not reached" (with stroke time monitoring)
SM-D2 (inductive PNP):
  • 2× PNP NO contacts for OPEN and CLOSED end positions; 24V DC; direct connection to PLC digital inputs (PNP-compatible) without interposing relays
SM-N2 (inductive NAMUR):
  • 2× NAMUR signal outputs; evaluation via Zener barrier or galvanic isolator; NAMUR standard EN 60947-5-6 (damped <1mA = switch actuated; undamped >3mA = switch open)
  • Evaluation unit converts NAMUR signal to 24V DC PLC-compatible signal
Typical uses of position feedback signals in the process control system:
  • Stroke confirmation: After a positioning command (OPEN or CLOSE), the PLC waits for confirmation from the limit switch box within a defined stroke time; if confirmation does not arrive → alarm "stroke monitoring" or "actuator blocked"
  • Process interlocks: Other plant sections can only start once the valve is safely in its end position (e.g. pump start only permitted when butterfly valve is fully open)
  • Status visualisation: Valve position displayed in SCADA/DCS operator screens as green (OPEN) / red (CLOSED) / yellow (in motion / fault)
  • SIL requirements: In safety-instrumented systems (SIL 1–3), valve position feedback is an essential element of the safety function; ATEX N2 version and redundant wiring per IEC 61508/61511
Yes – the limit switch box is a standard module in the FERGO automation package, which can be supplied factory-assembled and tested as a complete unit on the process valve. The typical configuration of a complete automated valve assembly:
  1. Process valve (butterfly valve, ball valve, knife gate valve etc.) with ISO 5211 actuator mounting flange
  2. Pneumatic part-turn actuator (DA or SA), direct-mounted on the ISO 5211 flange
  3. NAMUR solenoid valve (3/2 or 5/2), mounted on the NAMUR hole pattern of the actuator
  4. Limit switch box (Switchmaster), also mounted on the NAMUR hole pattern or side flange
  5. Optional: Inductive sensor (IFM series) as an alternative to the limit switch box for contactless IO-Link position detection
Advantages of the factory-assembled package:
  • Factory-aligned and function-tested – correct switching point setting and torque verification before dispatch
  • All components mechanically and electrically matched – no incompatibilities in flange dimensions, torque ratings, or interfaces
  • Minimum on-site installation time: one unit, four bolts, one air line, one cable set
  • Unified documentation: one data sheet package and one CE declaration of conformity for the complete assembly
Contact: shop@fergo-valve.com | +49 21 31 / 15 39 28-0 | Mon–Fri 8:00–17:00.