In the first part of 2021 CAREL has widened its range of I/O expansions with the development of the new Digital Input expansion board.
I/O expansions are modules that can be added to a typical air conditioning application so as to increase the number of inputs and outputs available on the controller and consequently optimise the flexibility and modularity of the solutions.
One of the most common uses involves ventilation sections comprising several fans with electronic motors; in this case, the speed of the individual devices needs to be monitored in order to check their operating status and act on the other fans accordingly if one of them fails. CAREL has for many years now offered all of the tools needed to support large systems, such as air handling units or dry coolers, in which the fans are equipped with electronics that communicate via Modbus, making it possible to directly monitor their operating status.
However, units that are smaller in size and capacity have simpler and more economical fans that do not feature serial communication and provide a pulse signal based on the rotation speed, which can be read by fast digital inputs. This is the basis for the development of CAREL’s new Digital Inputs expansion board, an ideal solution for all cases where numerous digital inputs (including fast inputs up to 500 Hz) need to be read, however while limiting the total number of I/Os and space required, adding only those that are needed.
One typical example involves so-called “in row units” used for cooling data centres, highly compact units that do not require complex device control architecture or specific sensors for their operation. These feature a single ventilation section with at least 8 fans in parallel, which need to be monitored individually. In this case, reading the signal is a simple and effective way to verify operation, as well as being a more economical solution than installing expensive air flow-rate sensors.
The new expansion board features a high number of digital inputs to ensure maximum flexibility in different applications: this is essential on units where the main controller features a limited number of inputs and outputs, while multiple digital inputs need to be connected, for example to detect alarms or various signals.
The entire range of I/O expansions can be integrated into solutions based on the CAREL pCO and c.pCO programmable controller platforms, or into architecture using different controllers.