intelligent I/O

Hi.Can I find out why and how we use intelligent I/O modules.Especially,where do we need them and how to operate them.
thank you all.

more info, please

The term "Intelligent I/O" is used by many suppliers in a variety of ways. There isn't a single definition, but in general it indictes that functions in addition to the basics. In general conventional I/O just reads the status of a signal (ON or OFF for discrete) or the value of a process signal (12 mA = 2048 with analog for example). Remote I/O is the same, but includes a communications link for reading the status or value from a device in a different physical location.

With intelligent I/O some kind of function adds to remote I/O capabilities. This may be just diagnostics to indicate bad modules or loss of signal. It may add some logic capabilities such as limit alarms turning on an output when an analog value drops beow a set point, or it may allow interlocks, so that for example a given output may only turn on if two designated inputs are also turned on. At teh extreme, a micro PLC networked to a master may be considered an extreme example of intelligent I/O.

Intelligent I/O is often used with PC based control or SCADA systems, since the PC doesn't have built in I/O capabilites. It is also used where failure of the PC, master controller failure, or communications latency can cause damage or personnel hazards. For example, it could be used in a pump station connected by radio telemtry to a SCADA PC. You wouldn't want the pump damaged if the wet well runs low, so you use the local intelligent I/O to turn off the pump on a low level float switch signal even if the SCADA master says it should run. That way, the time elapsed between the float switch tripping and the PC getting the signal and deciding to turn off the pump and then sending the signal back to turn off the pump won't let the pump run dry.