AutomationDirect Logo Sensors Frequently Asked Questions

 

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Question: Can proximity sensors be connected in series?
Answer: Yes. The number of proximity sensors connected in series is dependent on the available voltage to energize the PLC input or load. This voltage is calculated as the sum of voltage drops across each sensor subtracted from the available power supply voltage. Let's use as an example three of the AutomationDirect APS24 series 3-wire NPN sensors, where the brown wire is positive, the black wire is the output, and the blue wire is the negative. The load will be a PLC input. By connecting the sensors in series, all of the sensors must be activated in order for the PLC to receive an input signal. Start by connecting the brown wire (BN+) of each sensor in a daisy chain configuration to the positive terminal (+) of a 24 VDC power supply. Next, connect one side of the load (PLC input module) to the first sensors's brown wire (BN+) and the other side to the black wire (BK). Then connect that same sensor's blue wire (BU-) to the second sensor's black wire (BK). Connect the second sensor's blue wire (BU-) to the third sensor's black wire (BK). For the final termination, connect the third sensor's blue wire (BU-) to the negative (-) terminal on the 24 VDC power supply. In the case of a 2-wire sensor using a sinking configuration, connect one side of the load (PLC input) to the positive terminal (+) of a 24 VDC power supply and the other side of the load to the positive (BN+) of the first sensor. Then, connect the negative (BK or BU-) of the first sensor to the positive (BN+) of the adjacent sensor, continuing this patterns as many times as needed, staying within the voltage restrictions previously mentioned.
FAQ ID: 303

Question: What is the smallest AC powered proximity sensor that AutomationDirect offers?
Answer: The 12 mm diameter VM1 series is a 2-wire, 20-253 VAC sensor with sensing ranges from 2 mm to 4 mm, an axial or quick-disconnect cable, and a N.O. output signal.
FAQ ID: 305

Question: Does AutomationDirect offer capacitive type proximity sensors?
Answer: Yes, the CT series 30mm diameter, 3-wire sensors with sensing ranges from 2mm to 20mm, metal housing with axial cable, metallic and non-metallic detection, and a N.O. or N.C. output signal.
FAQ ID: 306

Question: What is the operating voltage for AutomationDirect proximity sensors?
Answer: The majority of AutomationDirect proximity sensors operate at 10-30 volt DC power. However, the VT1, VK1, and VM1 series operate at 20-253 volt AC power.
FAQ ID: 307

Question: Can I connect only two wires of a 4-wire sensor?
Answer: A 4-wire sensor is designed for use of at least three of the four wires. Wire usage is based on connecting the sensors power (+), common (-), and either a Normally Open (N.O.) or Normally Closed (N.C.)output, or both outputs. The sensor will not operate as a 2-wire device.
FAQ ID: 309

Question: What is the minimum distance that two proximity sensors can be installed parallel to each other?
Answer: When placing sensors parallel to each other, always leave a minimum distance equal to the diameter (12mm, 18mm or 30mm)of the sensors.
FAQ ID: 310

Question: Does AutomationDirect offer sensors that are protected against washdown?
Answer: Yes, the majority of sensors offered by AutomationDirect have an IP67 rating, which is rated for brief, intermittent submersion. Always check the specifications before selecting a device for any application.
FAQ ID: 339

Question: What is the difference between inductive and capacitive sensors?
Answer: The primary difference is sensing material. Inductive sensors only detect metallic objects while capacitive sensors will detect other materials such as wood, paper, liquids, cardboard, etc.
FAQ ID: 340

Question: Why is switching frequency important?
Answer: Switching frequency is the speed in which a sensor detects an object, resets, and senses another object. For example, if a sensor has a switching frequency of 100 Hz (100 cycles peer second) it can detect a maximum of 100 objects per second. This is very critical in many applications such as gear rotation measurement.
FAQ ID: 341

Question: Does AutomationDirect offer an AC proximity sensor in a quick-disconnect model?
Answer: Yes, the 12mm VM1 and 18mm VK1 series of AC Inductive proximity sensors are available with an M12 4-pin connector. They can be used with the optional 2 meter and 7 meter M12 quick-disconnect cables also offered by AutomationDirect.
FAQ ID: 404

Question: Does AutomationDirect offer TTL sensors?
Answer: Sorry, AutomationDirect does not offer TTL sensors at this time.
FAQ ID: 405

Question: How do I know what size proximity sensor to use?
Answer: It depends on two factors: (1) mounting space and (2) sensing distance. Each application has a specific amount of space available for the sensor and a requirement of how close the sensor can be mounted to the sensing object.
FAQ ID: 457

Question: What is the difference between a shielded and unshielded proximity sensor?
Answer: There are two major differences between a shielded and an unshielded proximity sensor. With a shielded sensor, only the face of the sensor is exposed and can be mounted flush with the sensing object. In many applications flush mounting is a requirement. With an unshielded sensor, the face and a small portion of the sides are exposed. This allows detection of objects from the side as well as the front, but does not allow mounting flush with the object as the sensor would always be activated. Unshielded proximity sensors allow for greater sensing distances.
FAQ ID: 458

Question: How do I determine which type of proximity sensor output I need, NPN or PNP?
Answer: PNP sensors are current sourcing devices and NPN sensors are current sinking devices. A current sourcing sensor must be connected to a current sinking input. Likewise, a current sinking sensor must be connected to a current sourcing input, so you must know the input circuitry of the device you are connecting with the sensor. Most AutomationDirect PLC input modules (except 305 series) allow NPN or PNP sensors to be connected. This is sometimes determined by what other type of devices are being connected to the PLC module.
FAQ ID: 459

Question: How do I choose between a Normally Open (NO) and Normally Closed (NC) sensor ouput?
Answer: Normally Open sensors do not pass power to the PLC until an object is detected. Normally Closed sensors always pass power to the PLC until an object is detected. The majority of AutomationDirect sensors have Normally Open outputs, however, the PKW, PMW and CT1 series sensors are available with Normally Closed outputs.
FAQ ID: 460

Question: Why use a sensor with a quick-disconnect cable versus an axial cable?
Answer: A sensor with a quick-disconnect cable allows for easy replacement of the sensor by eliminating the need for rewiring. This is important when considering machine or operation downtime associated with replacing a sensor. There is a cost difference versus a sensor with an axial cable since the quick-disconnect cable must be purchased seperately.
FAQ ID: 461

Question: What is the difference between 2-wire, 3-wire, and 4-wire sensors?
Answer: 2-Wire Sensors: Allows either NPN or PNP output (Don’t have to select!) 3-Wire Sensors: Most commonly used. When ordering, must choose an NPN or PNP output 4-Wire Sensors: Allows either NO or NC output (Don’t have to select!) Must choose NPN or PNP output when ordering
FAQ ID: 462

Question: Can a proximity sensor be installed in a vibrating environment?
Answer: Yes, if installed within a frequency range of 10 to 55 Hz, with a maximum amplitude of 1 mm, and a duration in any axis for a maximum of 30 minutes.
FAQ ID: 482

Question: What is the leakage current of an AutomationDirect proximity sensor?
Answer: AutomationDirect offers a wide range of proximity sensors, with each model having its own specifications. To find the leakage current for a particular sensor, reference the Specifications chart for the sensor, which can be found in the catalog or on the AutomationDirect Web site.
FAQ ID: 547

Question: Can you parallel ac inductive sensors?
Answer: Yes.
FAQ ID: 617

Question: Does AutomationDirect offer an AC sensor with a Normally Closed output?
Answer: No, AutomationDirect does not offer AC sensors with Normally Closed ouputs at this time.
FAQ ID: 618

Question: Will a magnet trip an inductive proximity sensor?
Answer: If there is a sufficient amount of ferrous metal in the magnet there is the possibilty of the sensor becoming activated.
FAQ ID: 679

Question: Does AutomationDirect offer a sensor that measures levels?
Answer: AutomationDirect offers three series of ultrasonic sensors with ranges up to 2,500 mm with Normally Open or Normally Closed PNP or NPN output, or analog 0-10 VDC ouput. The SU series, the TU series, or the UHZ series.
FAQ ID: 680

Question: Does AutomationDirect offer a photoelectric sensor that is submersible??
Answer: The majority of photoelectric sensors offered by AutomationDirect have an IP67 rating, which is protected against the effects of temporary immersion between 15cm and 1m, with a tested duration of 30 minutes. These sensors are not recommended for continuous immersion applications.
FAQ ID: 766

Question: Does AutomationDirect offer an AC powered photoelectric sensor?
Answer: Yes, AutomationDirect offers three series of AC photoelectric sensors. The MQ series, the MV series, and the FG series.
FAQ ID: 933

Question: What type of rubber is used for the rubber boot on the ABM series of limit switches offered by AutomationDirect?
Answer: NBR 55 (Nitrile Butadiene Rubber 55 Shore) General Description: Also known as Nitrile Butadiene (NBR), or Buna-N. It is a copolymer of butadiene and acrylonitrile which makes it exceptionally resistant to petroleum based oils and hydrocarbon fuels. It is also good against fats, greases, and some chemicals. Nitrile Rubber has a temperature range of -40º F to +250º F.
FAQ ID: 949

Question: How do inductive proximity sensors work?
Answer: Inductive proximity sensors are used to detect the presence of metallic objects without actually contacting the object. Their high-speed switching and small size make them indispensable in automation applications. Inductive proximity sensors consist of an oscillator driven coil. The oscillator creates an electromagnetic field which appears at the active face of the sensor. If a metal target enters this area, the electromagnetic field is reduced and the sensor switch turns on or off. Some typical inductive sensor applications are: counting metallic objects, monitoring the position of elements in a machine, sensing the presence of metallic parts such as screws, and measuring the rotational speed of axial detecting cams.
FAQ ID: 1053

Question: What is the difference between the PUR (polyurethane) and PVC (polyvinyl chloride) sensor cables.
Answer: Use PUR (polyurethane) jacket for oily and direct sunlight applications. Use PVC (polyvinyl chloride) jacket for typical industrial applications
FAQ ID: 1118

Question: How do I adjust the SET and RESET on the PSD25 series sensors?
Answer: Simplified means to set the PSD25 series pressure sensor. The SET and RESET adjustments (Rings) are mechanically interlocked to prevent setting less than the minimum offset required by the sensor. You cannot use the same pressure setting for the SET and RESET. There must be some hysterisis (offset) to the settings. This is not defeatable. All the directions assume you are looking at the cable end of the sensor. 1. Unlock the sensor adjustments (top most ring). The unlock symbol will line up with center arrow when unlocked. - Rotate the LOCK ring clockwise until it stops 2. Adjust the SET point (2nd ring from top) to it's lowest setting. - Rotate the SET ring counter-clockwise until it stops. - The RESET ring will start moving at some point to maintain the mimimum offset. 3. Adjust the RESET point (3rd ring from top) to the desired reset point. This is the pressure at which the sensor will turn off after being turned on. This has to be offset from the SET to prevent chattering/rapid cycling. - Rotate the RESET ring clockwise to the desired reset point. - The SET will move also to maintain the offset. 4. Check the setting of the SET ring. You cannot adjust the SET point lower than the reset so the reset may move. - If this needs to be adjusted, the RESET will be affected to maintain the offset.
FAQ ID: 1181