by Michael Jackson, Brian Condell, and Konrad Scheuer
Smart sensors often steal the limelight in articles and videos heralding the latest achievements and future possibilities of Industry 4.0. However, while sensors act as the 'eyes and ears' that allow a programmable logic controller (PLC) to know what's happening on the factory floor, actuators (Figure 1) are the unsung heroes that provide the 'muscle' that gets things done. The unbalanced focus on sensors could be attributable to the fact that many people aren’t aware that making actuators ‘smart’ can deliver significant rewards for factory managers. This blog explores some of these benefits before presenting a reference design demonstrating the advantages of using IO-Link to enable a practical smart factory actuator to communicate with a PLC. To catch up on the previous blog post find it here.
Figure 1 Actuators - the unsung heroes on the factory floor - are becoming smarter
Actuators traditionally used mechanical principles (pneumatic, hydraulic) to open and close valves, but electrically controlled motors have replaced these in many applications. Nonetheless, actuators will always have moving parts. These create friction and require ongoing monitoring and maintenance to prevent the type of failure that could cause production to stop unexpectedly. The addition of low-voltage electronics allows factory operators to perform their tasks in much cleverer ways. Some of the advantages microelectronic technology brings to actuators include the following:
Analog Devices and TMG TE collaborated to design the MAXREFDES278# 8-Channel Solenoid Actuator reference design (Figure 2), based on the MAX22200 1A Octal Integrated Serial-Controlled Solenoid Driver IC (with integrated FETs) and the MAX22514 IO-Link transceiver (with integrated protection). The MAXREFDES278# has an industrial form factor, with each solenoid channel having a dedicated 2-way terminal block. It measures 85mm x 42mm and uses an industry-standard M12 connector, allowing a 4-wire IO-Link cable to connect it to an IO-Link master transceiver like the MAX14819.
Figure 2 MAXREFDES278# IO-Link 8-Channel Solenoid Actuator Reference Design
This reference design can be powered in two ways. For example, the first is through the IO-Link master directly (delivering up to 800mA total load) or using an external power source to provide higher currents. The MAX17608 current limiter is used, with over-voltage (OV), under-voltage (UV), and reverse protection to ensure that the IO-Link portion is always powered and so that no current can flow back to the IO-Link master. The advantage of using IO-Link for data communication is that it carries four different types of transmissions - Process Data, Diagnostics, Configuration, and Events which can flag if the actuator malfunctions allowing it to be quickly attended. Another advantage of using IO-Link is that it makes the actuator 'network agnostic', meaning it will work on any industrial network, so engineers don't need to worry about which protocol their actuator design uses.