Question
How can IO-Link device microcontrollers overcome the challenges associated with adhering to the timing requirements specified in the IO-Link standard?
Answer
An IO-link device microcontroller is expected to perform multiple tasks simul- taneously, which can cause difficulty in responding to a request within the acceptable specified time window. This is especially true if performing a task from which the microcontroller cannot be interrupted. A typical solution for this timing challenge is to use a second microcontroller to manage the IO-Link stack, thereby maintaining a more constant response time interval between the IO-Link device and the IO-Link master. However, this is a highly inefficient approach because it uses more power and requires a much larger PCB and therefore a larger sensor enclosure. A superior alternative is to use a transceiver capable of managing both the data link and physical layers in the communication pathway. By unburden- ing this task from the device microcontroller, this transceiver enables the design of even smaller, more complex, higher functioning, and cost-effective industrial field instruments.
Introduction
“To do two things at once is to do nothing”—while this take on multitasking by the Latin writer Publilius Syrus might be extreme, there are some circumstances where multi- tasking can lead to tasks not being performed in the way they were initially intended or on time. As industrial processes become more complex, field instruments like sen- sors and actuators have evolved to perform several different tasks simultaneously, including maintaining regular communication with a process controller. This imposes additional overhead on the device microcontroller that must be carefully managed or process data can be lost, leading to production downtime (the very thing that modern industrial communication protocols are supposed to reduce).
IO-Link Timing
IO-Link is a 24 V, 3-wire industrial communications standard that enables point- to-point communication between industrial devices and an IO-Link master that, in turn, communicates with higher level process control networks.
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