The limit switch AD-SMK 340 GVD compares the measuring value of a 2- or 3-wire-transmitter at the input with the preset values. If the measuring signal exceeds the set value, or is below it, the relevant output relay reacts according to the preset function. The standard signals (4–20mA, 0–10V) are possible as analogue input value without additional switch-over. The limiting values must be set at the keys 0–99% at the front. The output functions 2max, 2min or 1max/min as well as the resting or working principles of the output relays are also adjustable at the front. With operating mode 2max/2min, the hysteresis at both channels is approx. 1%. Input, outputs and the supply voltage are galvanically sepa- rated from each other.



Monitoring and signalling of limiting values of analogue measuring signals such as through flow, height levels, temperature etc.

Specific characteristics

  • Transmitter feeding voltage.
  • Two limiting values, digital freely adjustable up/down keys at the front.
  • Indication of limiting values and relay condition via LED at the front.
  • 23 mm wide serial housing with connection terminals, which can be pulled off.

Business data

Order number


Safety instructions pdf ad-safety-instructions.pdf (43 kB)

Technical specifications

Input current
Measuring range 4 ... 20 mA
Input resistance 25 Ohm
Input voltage
Measuring range 0 ... 10 V
Input resistance 100 kOhm
Transmitter supply
Open-circuit voltage < 20 V
At 20 mA > 18 V
Current limit < 30 mA
Relay output
Maximum switching load AC 250 V, 2 A
Maximum switching load DC 50 V, 2 A
Contact construction Changeover contact
Switching operations mechanical 10000000
At 230V/2A AC, cos(phi)=1 600000
At 230V/2A AC, cos(phi)=0,4 200000
At 24V/1 A DC 200000
Voltage range AC 50 ... 253 V AC, 50/60 Hz
Nominal voltage AC 230 VAC
Voltage range DC 20 ... 253 V DC
Nominal voltage DC 24 V DC
Power consumption AC/DC 3,5 VA / 1,6W
Transmission behaviour
Accuracy +/- 1 % of full scale
Temperature influence 100 ppm/K
Response time ~ 20 ms
Dimensions (WxHxD) 23x110x134 mm
Type of protection IP 20
Connection method Detachable terminal clamp
Terminals, wire cross section 2,5 mm² flex wire / 4 mm² one wire
Bolting torque terminals 0,5 Nm
Weight ~ 200 g
Manner of fastening 35 mm DIN rail 35mm
Protection circuits
Input Electrical surge protection
Power supply Electrical surge and reverse current protection
Electrical safety requirements
Product family standard EN 61010-1
Environmental conditions
Ambient temperature 0 ... 50 °C
Storage and transport -10 ... 70 °C (no condensation)
Galvanic isolation, test voltages
Input / output 3,75 kV (1 min.)
Signal / supply unit 4 kV (1 min.)
Product family standard EN 61326 1)
Emitted interference EN 55011, CISPR11 Cl. B
1)During electromagnetic disturbance minor changes in output signal are possible.

Block and wiring diagram




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