"Getting Started" FAQs about IO-Link products

[Kersten HEINS]

This list of Q and As are typical questions raised by customers considering use or evaluating ST IO-Link products, for example by participants of one of our webinars, see here for further information.
---------------------------------------------------------------------------------------------

Q1: Are ST IO-Link products compliant to the IO-Link specification version 1.1?
Q2: Does ST offer the IO-Link transceivers also as dies or wafer?
Q3: Can I use the L6362A transceiver as a general purpose line driver?
Q4: Are there any data buffers / or a frame handlers inside the IO-Link physical layer chips?
Q5: Can L6362A directly drive inductive or capacitive loads?
Q6: How strong surges can the L6362A physical layer sustain.
Q7: Why does L6362A offer two input pins ?
Q8: When we consider an actuator. How does it work with the transition from a standard IO mode to the IO-Link mode?
Q9: What are the requirements on transmission rate accuracy?
Q10: Does ST offer a full IO-Link solution for evaluation?
Q11: How can I run the IO-Link communication with ST evaluation kits?
Q12: What is the IODD and where can I find it?
Q13: Can I develop my own sensor or actuator application with IO-Link?
Q14: Can I also develop my own application for IO-Link master? How it works?
Q15: Can the IO-Link master P-NUCLEO-IOM01M1 be extended to multiport IO-Link master?
Q16: What are the limitations of IO-Link firmware running on ST P-NUCLEO kits?
Q17: How many slaves can a master manage?
Q18: Can you please give a few examples of applications where using IO Link should be a must?
Q19: Is the IO Link stack free for STMicroelectronics' users? Or with which license is required?
Q20: Do the eval boards come with installed IO-Link stack or where does the stack come from?
Q21: Are there any constraints in using the I/O-link standard on the evaluation kit?
Q22: Are there transceivers supporting chained/bus-wired I/O-Link sensors?
Q23: Is IO-Link also thought to replace KNX ?
Q24: About Arrow’s IO-Link Master Controller (based on STM32 MCU): Is the cost of the IO-Link stack avoided by using ARW-IOLM4P-STM32L4? When wlll the documentation for the SPI interface will be released?
Q25: What are the key benefits of IO-Link with respect to CAN?
Q26: In the STEVAL-IDP003V1 schematic I can't find any filter against high voltage induction spikes. Don't they cause problems in combination with long wires?
Q27: Is the IO-Link certification long, complex and costly using one of your solutions? For example for a device.
Q28: Is there the stack source code available for the STM32L073
Q29: What are typical examples of end devices with IO-link? For instance temperature sensor?
Q30: Is there any way to extend the maximum length of the cable to more than 20m?
Q31: Why does IO-link focus only on point to point and not more as a bus solution with multiple nodes?
Q32: I would like to know something more about cable specifications between master and device IO-Link nodes. Which is the minimum requirement?
Q33: Could you please explain the application (demo) of STEVAL-BFA001V1B ? I mean what is it supposed to demonstrate?
Q34: Is the IO-Link stack cost included in the ARW-IOLM4P-STM32L4 product?
Q35: What is the maximum cable length and communication speed?
Q36: Who develops the sensor side with IO-link? The sensor manufacturer? Any developers? If so, is there some protocol to match a sensor with IO-Link?
Q37: Is the number of slaves a restriction of the Master Chip (L6360)?
Q38: IO-Link is a kind of bus, what is the maximum speed allowed for communication?
Q39: Does IO-Link support data transfer by polling, on a timely basis and as event driven?
Q40: With the ARW-IOLM4P-STM32L4: can we run our own code on the device as well, or is it only for use with another CPU?
Q41: Which microcontrollers are supported with the IO-Link stack?
Q42: If we have existing Nucleo development boards, is there an IO-Link stack sample to download and run?
Q43: L6360: what advantage does the digital filter offer?

Q1: Are ST IO-Link products compliant to the IO-Link specification version 1.1?
A1: Both ST products, the L6360 as well as the L6362A are compliant to IO-Link specification version 1.1. They have been designed as general purpose transceivers and therefore fully protocol independent.
 
Q2: Does ST offer the IO-Link transceivers also as dies or wafer?
A2: Yes, this business option is available on request.
 
Q3: Can I use the L6362A transceiver as a general purpose line driver?
A3: Yes, besides the IO-Link communication both L6362A as well as L6360 chips can be used as general purpose transceivers. We enable user a direct access to control the power stages and also the receiver channels work completely independent from the drivers.
Q4: Are there any data buffers / or a frame handlers inside the IO-Link physical layer chips?
A4: No, there is a direct link between logic and the process sides of the transceivers. This gives a freedom to use the PHY as a general purpose transceiver. It is flexible for any change in communication specification.
Q5: Can L6362A directly drive inductive or capacitive loads?
A5: Yes, the power stage is equipped with embedded active clamp enabling to handle switch-off energy up to approximately 500mJ. Thanks to the active current limitation it is capable to drive also capacitive loads up to approximately 30uF.
Q6: How strong surges can the L6362A physical layer sustain.
A6: The power stage of the L6362A implements surge protection able to sustain 2A current peaks. It means considering surge generator coupling of 500Ohm, the maximum guaranteed level is 1000V.
Q7: Why does L6362A offer two input pins ?
A7: One input is used to define the signals polarity at the power stage as wells as at the receiver and the other one is used to control the power stage level.
 
Q8: We consider an actuator. How does it work with the transition from a standard IO mode to the IO-Link mode?
A8: The standard IO mode is typically not supported by IO-Link actuators as in standard IO mode the actuator is considered only as a signal receiver. So there is no way how to generate a wake-up request. It means actuators are always in the IO-Link mode.
 
Q9: What are the requirements on transmission rate accuracy?
A9: The maximum allowed transmission rate deviation at master is defined as +-0.1% by the IO-Link specification.
Q10: Does ST offer a full IO-Link solution for evaluation purposes?
A10: Yes, we provide evaluation kits for both IO-Link master (P-NUCLEO-IOM01M1) and sensor (P-NUCLEO-IOD01A1). Both tools come preloaded with IO-Link software and can run IO-Link communication out-of-the-box.
 
Q11: How can I run the IO-Link communication with ST evaluation kits?
A11: A graphical user application for PC/Laptop can be used to configure the communication and visualize the process data. The application was developed by our partner company TEConcept and is available free after registration at http://www.teconcept.de/en/CloudAccess/
 
Q12: What is the IODD and where can I find it?
A12: IODD stands for "I/O Device Description". It is a file that contains all necessary properties and parameters needed for communication and proper function of a sensor or an actuator in the IO-Link system. IODD for our sensor P-NUCLEO-IOD01A1 can be downloaded free of charge at www.io-link.com (IODDfinder).
 
Q13: Can I develop my own sensor or actuator application with IO-Link?
A13: Yes, the software package provided by TEConcept for ST IO-Link device includes a demo project for a free IDE System Workbench for STM32 which can be used to develop own application with IO-Link.
 
Q14: Can I also develop my own application for IO-Link master? How it works?
A14: Yes, P-NUCLEO-IOM01M1 provides an SPI interface allowing user to develop his own application and to use the board as an IO-Link master node. TEConcept provides a demo application project for this based on STM32 NUCLEO-F746ZG running the Low-level IO-Link Master Access Module.
 
Q15: Can the IO-Link master P-NUCLEO-IOM01M1 be extended to multiport IO-Link master?
A15: Yes, the kit can be extended up to four master ports using additional master expansion shields STEVAL-IOM001V1.
 
Q16: What are the limitations of IO-Link firmware running on ST P-NUCLEO kits?
A16: The IO-Link stack provided with ST evaluation hardware is developed by the company TEConcept and it is aimed for evaluation purpose. Therefore the Device stack generates a reset after 30 minutes of operation. Full featured stack is available from TEConcept.
Q17: How many slaves can a master manage?
A17: The IO-Link standard in general does not limit the number of slaves connected to an IO-Link Master module, however only one device shall be connected to each port (point-to-point topology). The P-NUCLEO-IOM01M1 kit supports up to four port connections.
 
Q18: Can you please give a few examples of applications where using IO Link should be a must?
A18: IO-Link technology is especially needed in smart sensor applications where high requirements on diagnostics and configurability are given and system availability and low down-times are mandatory (e.g. inertial sensors, RFID readers/writers).
 
Q19: Is the IO Link stack free for STMicroelectronics' users? Or with which license is required?
A19: The IO-Link stack is preloaded in our P-NUCLEO-IOD01A1 and P-NUCLEO-IOM01M1 and it's free for evaluation. A user application code can also be developed based on our evaluation package, however for production and commercial use of IO-Link compliant equipment the license has to be obtained from TEConcept GmbH.
 
Q20: Do the eval boards come with installed IO-Link stack or where does the stack come from?
A20: Yes, our evaluation kits (P-NUCLEO-IOM01M1 and P-NUCLEO-IOD01A1) come preloaded with IO-Link software and can run IO-Link communication out-of-the-box. A graphical user application for PC/Laptop can be used for system evaluation which is available free after registration at http://www.teconcept.de/en/CloudAccess/
 
Q21: Are there any constraints in using the I/O-link standard on the evaluation kit?
A21: Since the stack preloaded in our P-NUCLEO is aimed for evaluation only, there are a few limitations implemented. One of them is that the Sensor board generates a reset every 30 minutes of operation.
 
Q22: Are there transceivers supporting chained/bus-wired I/O-Link sensors?
A22: IO-Link is by definition strictly a point-to-point topology. Therefore there is always one Master port and one Device port connected by an IO-Link cable.
Q23: Is IO-Link also thought to replace KNX ?
A23: No, IO-Link technology is mainly suited for use in smart industrial automation while KNX is better fitting in home and building control.
 
Q24: About Arrow’s IO-Link Master Controller (based on STM32 MCU): Is the cost of the IO-Link stack avoided by using ARW-IOLM4P-STM32L4? When wlll the documentation for the SPI interface will be released?
A24: Yes, the stack is in this case included in the ARW-IOLM4P-STM32L4 price. Full documentation for the SPI interface can be obtained from TEConcept
 
Q25: What are the key benefits of IO-Link with respect to CAN?
A25: The key benefit of IO-Link is that it's been developed specifically for the purpose of connecting industrial sensors and actuators by the major industrial producers. It's also backwards compatible with standard IOs (IEC 61131-2), so it ensures wide interoperability without the need to replace wiring infrastructure.
 
Q26: In the STEVAL-IDP003V1 schematic I can't find any filter against high voltage induction spikes. Don't they cause problems in combination with long wires?
A26: The L6362A IO-Link sensor transceiver is designed to be immune against EMC overstress. In order to ensure the immunity at the application level we recommend to use filtering capacitors (as in the STEVAL-IDP003V1 or STEVAL-IFP017V3)
 
Q27: Is the IO-Link certification long, complex and costly using one of your solutions? For example for a device.
A27: IO-Link doesn't require real certification, each manufacturer's responsibility is to ensure the conformity according to the test specification defined by the IO-Link consortium, so it is a very smooth process.
 
Q28: Is there the stack source code available for the STM32L073
A28: IO-Link stacks are ported to various ST MCUs and available at our partner TEConcept. ST doesn't provide stack source codes.
 
Q29: What are typical examples of end devices with IO-link? For instance temperature sensor?
A29: Temperature sensor, pressure sensor, position sensor etc.
 
Q30: Is there any way to extend the maximum length of the cable to more than 20m?
A30: In fact 20 meters is really the maximum allowed IO-Link cable length, however the IO-Link master can be used as a decentralized module connected by various fieldbuses allowing longer cables.
 
Q31: Why does IO-link focus only on point to point and not more as a bus solution with multiple nodes?
A31. The positioning has been defined at the very beginning, the target was to dedicate it to sensors & actuators, keep it as simple as possible and backward compatible with switching inputs / outputs.
 
Q32: I would like to know something more about cable specifications between master and device IO-Link nodes. Which is the minimum requirement?
A32: Cable requirements are defined in details in the IO-Link standard (IEC 61131-9). Key parameters are: length ~20m max, overall loop resistance Rleff ~ 6Ω max, effective line capacitance Cleff ~ 3nF max.
 
Q33: Could you please explain the application (demo) of STEVAL-BFA001V1B ? I mean what is it supposed to demonstrate?
A33: STEVAL-BFA001V1B is intended to demonstrate condition monitoring for mechanical devices like bearings as viabrations are sensed by the embedded accelerometers. The IO-Link is in this case supported only by hardware design, the IO-Link stack is not yet ported to this board, and nevertheless it is foreseen to come soon.
 
Q34: Is the IO-Link stack cost included in the ARW-IOLM4P-STM32L4 product offered by Arrow?
A34: Yes, price of the stack (license) is included in the ARW-IOLM4P-STM32L4 as this MCU comes already pre-programmed with the stack.
 
Q35: What is the maximum cable length and communication speed?
A35: The maximum cable length defined by the IO-Link specification is 20 meters, the maximum communication speed is 230.4 kbit per second.
 
Q36: Who develops the sensor side with IO-link? The sensor manufacturer? Any developers? If so, is there some protocol to match a sensor with IO-Link?
A36: Key industrial sensor manufacturers can be found on the IO-Link.com website.
 
Q37: Is the number of slaves a restriction of the Master Chip (L6360)?
A37: Each L6360 can interface 1 device (slave) as it implements one IO-Link channel. This configuration has been chosen to enable users full flexibility in the application.
 
Q38: IO-Link is a kind of bus, what is the maximum speed allowed for communication?
A38: Maximum communication speed is 230.4 kbit per second.
Q39: Does IO-Link support data transfer by polling, on a timely basis and as event driven?
A39: Process data are exchanged periodically over the IO-Link according to the defined cycle time.
 
Q40: With the ARW-IOLM4P-STM32L4: can we run our own code on the device as well, or is it only for use with another CPU?
A41: ARW-IOLM4P-STM32L4 firmware can’t be modified, a host MCU is needed in the Master application
 
Q41: Which microcontrollers are supported with the IO-Link stack?
A41: Master as well as Device stacks are available for STM32 (Cortex M0, M3 & M4). Device stack is available also for STM8L / STM8S.
 
Q42: If we have existing Nucleo development boards, is there an IO-Link stack sample to download and run?
A42: The IO-Link Stack is not available for download, the only way to obtain it is to get the pre-programmed P-NUCLEO kit.
 
Q43: L6360: what advantage does the digital filter offer?
A43: Purpose of the digital filter is to de-bounce the discrete input, to filter higher frequency noise
 

Customer Note:
1) If you would like to submit a comment, feedback or any suggestions about this particular article or our knowledge database in general you can post by email to kb.feedback@st.com
2) If you need specific (product) support please refer to our Support Home (https://www.st.com/content/st_com/en/support/support-home.html) where you choose from a variety of online support options and select a service which fits your requirements best.