We want to connect the lift signals via CAN-bus I/O-adapter. Is this limited to a certain amount of I/Os?
The displays are communicating with the I/O-modules via CAN-open messages, which are defined in the CAN-open Lift standard. The modules of all manufacturers supporting this standard can be used. On the market, these modules are offered with 8, 16 or 32 I/Os and some of them can also be extended with more I/Os.
Directly via the CAN-bus there can be up to 63 modules (64 minus number of displays) connected. This should not be necessary very often in practice. Each module theoretically could supply up to 128 signals. Thanks to the possibility of connecting a repeater to the network, there is basically no limit to how many I/Os can be connected.
When it gets to the display's configuration of these signals, it looks differently though. To be able to design the configuration of the signals clearly, we limited the number of configurable I/Os to 127. This should be more than enough in most cases. These 127 signals can be distributed freely among one or many modules, which also can be located on different places in the lift depending on where the signals are available (e.g. one module on top of the cabin, one in the controlling).
In addition to the I/O signals, the display can also directly evaluate the sensor data of various sensors. This way e.g. the current load can be displayed in kilogramm or the position and velocity of the cabin, without needing I/O-modules.
In the figure below, the general wiring of an I/O-module with 16 I/Os is depicted. More possibilities of Connecting various I/O modules, displays and sensors can be found in the installation section.
