Digitally switching sensors are available with a PNP, NPN or Namur output; measuring sensors come with voltage output (0 … 10 V) or current output (e.g. 4 ... 20 mA or 0...10 mA).
The voltage drop across each conducting sensor reduces the voltage available to drive the load. The number of proximity switches which can be connected in series is therefore limited and may be worked out by summing the individual voltage drops plus the load requirement.
3-wire DC sensors may be connected in parallel as shown. A parallel connection, however, must incorporate a decoupling diode.
Connection diagrams
The specified diagrams indicate the undamped output. A sensor is in a damped state when an object is located in within its scanning range. In the diagrams Z denotes the typical load resistance position; Uz denotes the voltage applied to this load resistance. If Uz = high (≈ +Vs), then current flows; if Uz = low (≈ 0 V), then no current flows via the load resistance. Load resistance between output and +Vs is referred to as pull-up resistance, load resistance between output and 0 V as pull-down resistance.
PNP- or NPN output
Sensors with a PNP or NPN output have a 3-wire design (+Vs, output and 0 V) and operate with direct current (DC). The load resistance of PNP sensors is between output and 0 V (pull-down resistance), while load resistance of NPN sensors is between +Vs and output (pull-up resistance). As a result, the PNP output is connected to the positive voltage supply during switching (positive switching output), whereas the NPN output is connected to the negative voltage supply during switching (negative switching output).
Normally open contacts and/or normally closed contacts define the switching function. Normally open contacts are referred to as normally open (NO), normally closed contacts as normally closed (NC). During damping with an object, sensors with normally open function establish contact connections (Uz = high), while sensors with normally closed function disconnect connections (Uz = low).
Explanatory notes on the connection diagrams
The specified diagrams indicate the undamped output. A sensor is in a damped state when an object is located in within its scanning range. In the diagrams Z denotes the typical load resistance position; Uz denotes the voltage applied to this load resistance. If Uz = high (≈ +Vs), then current flows; if Uz = low (≈ 0 V), then no current flows via the load resistance. Load resistance between output and +Vs is referred to as pull-up resistance, load resistance between output and 0 V as pull-down resistance.
Mounting and mounting procedure
To rule out unintentional interference of the measuring field and to achieve maximum sensing distances, it is required to follow the mounting instructions and to maintain the specified minimum distances. If the minimum distances are undercut, a reduction of the sensing distances is expectable. A sensor test directly at the application is recommended.
Correction factors for different installation situations specified in the sensor data sheet have priority over the general guidelines below.
There must be a space equal to the diameter of the sensing head, with no metal interference. Following this rule the electrical field strength is less attenuated, which enables a larger sensing distance.
When mounted in ferromagnetic material these sensors require a space (x) behind the active area that is free of metal. Sensors can be installed shielded (flush) when mounted in non ferrous materials (colored metals etc.). Always read and follow the installation instructions for distance measuring sensors.
Minimum distances must be observed to prevent oppositely positioned sensors from affecting each other.
Maximum installation torque
To avoid damage to the proximity switches during mounting, the default torque value should not be exceeded. Reduce torque values by 30 % at the sensor’s face.
Mounting instructions for housings without threads
Strong, occasional housing loads, like those which occur e.g. during fixing with headless screws, must be avoided (IFRM 03, 04, 06). Incorrect installation can lead to irreversible damage to the proximity switch. Sensors with a housing diameter of 6.5 mm can be installed optimally with the plastic support bracket 10109474.
Cable dimensions
Set-up / Teach-In
Baumer Teach-In functions
Baumer AlphaProx sensors with linearized characteristic curve, factor 1 sensors and high sensitivity sensors have a teach function with several teach modes. This allows the measuring range to be freely configured within specified limits. If, for example, a small measuring range with a large signal amplitude is required, it is possible to limit this to a few millimeters. The operating direction of the analog output can also be inverted if required.
In addition, the switch-on and switch-off points of a digital output can be defined. These may lie both within and outside the individually programmed measuring range.
Teaching-in of the start position (e.g. 0 V), center position (e.g. 5 V) or end position (e.g. 10 V) of the measuring range. In this teach mode, the output characteristic curve can be shifted without changing the sensitivity or slope of the characteristic curve. It is used for electronic compensation of installation tolerances and thus enables quick and easy adjustment in series production.
The 2-point teach is used in applications in which two reference points (start and end position) can be approached. By adjusting the measuring range, the sensitivity or slope of the output characteristic curve can be perfectly adapted to the application and installation and mechanical manufacturing tolerances can be compensated. The first taught-in position always corresponds to the start value (e.g. 0 V) and the second to the end value (e.g. 10 V) Depending on the teach sequence, the output characteristic curve increases or decreases as the target object approaches.
Analog distance sensors with an additional digital output offer a window teach digital instead of a 2-point Teach analog. This allows defining a valid or invalid distance range between the target and sensor for the digital output - independent of the analog output signal. Depending on the teach sequence, the digital output is HIGH or LOW if the measured object is within the taught-in distance range. This teach function is used to define a separate switching signal, e.g. for an end position circuit, independently of the analog signal.
Factory Reset
All sensors with teach functions have a factory reset to reset the sensor to the factory settings.
