question..

[bathulagopi]

if a solenoid valve is connected to a controller.. what type of signal does it receive? 4-20mA, 1-5V?? is it analog or digital output?

if i have a level alarm switch low as a Digital Input, what is the Digital output of it? a Valve command?

I'm sorry im such a noob T_T im just a first year engineering student and i cant catch up with these things in school..

For your 1 question i agree with dinil

I guess you are a bit confused between input and output you should decide whether it is input or output with reference to a control system if there is input to control system and it is a digital then it is called as digital input (generally all switches and status signals come under this )like wise if there is output from control system and if it is digital it is called as digital output( generally all valves that operate with solenoid valves, beacons, relays, hooters etc comes under this )

and now if you have confusion difference between analog and digital signals try to find it from google lot of useful inf you will find

Good Luck

Gopi.
For your second question a signal from Level switch to Control system will be digital input and