What are Timestamp Inputs and Outputs?

Timestamp IO slices for the NX bus are very special units that allow for extremely high precision systems to be programmed and controlled. When your application requires that you know when an Input turned on, or wish to control the exact time an output turns on in a sub microsecond range of precision, you need Timestamp IO.

Timestamp Input units are models NX-ID3344 (4 point NPN) and NX-3444 (4 point PNP). These inputs not only report that the input has turned on, but also the exact time that this occured. This is possible due to the highly accurate synchronized distributed clocks in an EtherCAT network. The response time for these units is 100ns (0.1 microseconds) on and off. The time of the change of state is communicated in the next EtherCAT Process Data update and the controller will have access to this value on the next cyclic execution of the user program. By determining the exact time that an input changed state, it is possible to perform calculations and enable a level of precision that is well beyond the cyclic update of the Process Data via EtherCAT normally possible. In fact no matter how fast a network updates, it will never be able to update quick enough to be more accurate that these units. 

Timestamp Output units are models NX-OD2154 (2 point NPN) and NX-OD2558 (2 point PNP). These outputs are controlled by setting the exact time that the system needs the output to change state in advance. This time is communicated from the controller to the NX IO unit via a normal EtherCAT Process Data update. However the unit is responsible for turning on at the exact time that has been set. The response time of these outputs is 300ns max, ie 0.3 microseconds. By calculating the exact time of the output in advance, an extremely precise change of state can occur, well beyond the capability of the controllers cyclic program execution. 

Combining Timestamp inputs and Outputs would allow a controller to precisely shift an input event to an output event, just by reading the switch on time, shifting it by a certain amount and sending it to the output unit.

These Timestamp outputs are used with the Flying Trigger system for OMRON vision, that allows a vision camera to be moved past a series of inspection pints. Function Blocks predict the exact time the camera needs to be triggered using data from the OMRON servo system, and the timestamp output precisely triggers the camera shutter. Despite the camera movement, the triggering of the camera is perfect, and allows non stop precision inspection to occur, drastically decreasing inspection times for rows and matrix arrangements of parts.