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This is probably a stupid question but I am new to IO link sensors.

When using IO link technology with a PLC (siemens s7-1200) can you connect devices that are not IO link sensors?

For example say I wanted to connect an existing normal push button to a IO link master, is it possible to cut the plug of the IO link cable and connect the button with the 3 required cores( positive, negative and the signal wire)?

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3 Answers 3

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When using IO link technology with a PLC (siemens s7-1200) can you connect devices that are not IO link sensors?

For example say I wanted to connect an existing normal push button to a IO link master

It depends on the IO Link master. Some allow you to turn off the IO Link functionality on a per port basis and use them as a standard input.

It's usually a waste of a master port though as you can get devices that convert 8 or 16 binary I/O points into IO-Link. Examples include:

https://www.ifm.com/us/en/category/055/055_020

https://www.balluff.com/local/us/productfinder/#/ca/A0009/cg/G0903?cal_iolink

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An IO-Link system consists of an IO-Link master and one or more IO-Link devices

That's a quote from Wikipedia IO-Link and basically it means that master and slaves have to be compatible: -

An IO-Link system consists of an IO-Link master and one or more IO-Link devices, i.e. Sensors or Actuators. The IO-Link master provides the interface to the higher-level controller (PLC) and controls the communication with the connected IO-Link devices.

When using IO link technology with a PLC (siemens s7-1200) can you connect devices that are not IO link sensors?

No, you can't.

For example say I wanted to connect an existing normal push button to a IO link master, is it possible to cut the plug of the IO link cable and connect the button with the 3 required cores( positive, negative and the signal wire)?

No, you can't.

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    \$\begingroup\$ Ok, thanks Andy \$\endgroup\$
    – David777
    Dec 6, 2020 at 15:02
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    \$\begingroup\$ @David777 why have you unaccepted the answer? \$\endgroup\$
    – Andy aka
    Dec 7, 2020 at 15:31
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say I wanted to connect an existing normal push button to a IO link master, is it possible to cut the plug of the IO link cable and connect the button with the 3 required cores

No. You would need to get an IO-link digital interface device and connect your push button to the interface. The interface would then communicate with the PLC over an IO-Link cable.

An IO-Link system is a form of point-to-point computer network connection. It runs a specific computer network protocol over the IO-Link cable between an IO-Link master and an IO-Link device, which could be a sensor (input) or actuator (output). The master and the devices need to have some built-in computing ability in order to implement the IO-Link protocol.

If you have an intelligent sensor (i.e. one with a built-in microcontroller) it can implement the IO-Link protocol itself and be plugged in directly to an IO-Link cable. Here's a random example of a pressure sensor with an IO-Link interface.

However a normal push button doesn't have a microcontroller, it can't implement the IO-Link protocol itself and therefore it can't be plugged in directly to an IO-Link cable. Instead you need to use an IO-Link sensor device as an intermediate device between your pushbutton and the IO-Link cable. You'll need an IO-Link sensor with a digital input. (In this context "digital" means a single line carrying ON or OFF information.) You'll need to wire your pushbutton to a digital input on a sensor. The sensor will read the state of the pushbutton and send the state over the IO-Link cable to the IO-Link master and then on to the PLC. (IO-Link digital input connectors also seem to provide 24VDC and ground connections so you can power your pushbutton circuit.)

While I suspect the idea of standardising IO-Link is that any manufacturers' products can be used, as you do have a Siemens PLC Siemens also make an IO-Link digital sensor, the K20. (If you click on the booklet icon to the left of the 3RK5010-0BA10-0AA0 model number a browsable list of other IO-Link devices should appear, if not already visible.)

This may seem a roundabout way of getting pushbutton input into a PLC but you specifically asked about IO-Link. An alternative is that your PLC may have digital inputs to which a pushbutton could be wired directly.

Siemens themselves or your usual PLC supplier should be able to provide you with technical help on how to use these products. A search engine should find a selection of documents and videos to let you learn more about IO-Link.

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  • \$\begingroup\$ How does this digital interface device differ from a IO link master device? Have you got any links of products? I don't quite understand what you mean \$\endgroup\$
    – David777
    Dec 7, 2020 at 10:26
  • \$\begingroup\$ @David777 In IO-Link jargon a device is a peripheral that connects to an IO-Link master over an IO-Link cable. I've extended my answer. Please comment if anything still isn't clear. \$\endgroup\$
    – Graham Nye
    Dec 7, 2020 at 18:43

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