Reading Analog Signals
Hi!
I wish to ask, how would one be able to read analog signals from a system using PLCnext.
e.g Let's say I want to read analog signal from a VT or CT connected to a phase line in the DB, what function would I use to be able to read these signals?
Comments
Hello Emmanuel,
we have analog input modules.
AXL F AI4 I 1H - Analogmodul - 2688491 | Phoenix Contact
What do you mean with "from a VT or CT connected to a phase line in the DB" ?
You do not need any functions to read analog values from these IOs just connected process data and the variables will be updated every taskcycle.
Hello Oliver,
What I mean is that, how do I read the signal coming from a current transformer or voltage transformer or any type of analog signal.
And also, how do I read or convert the word value as a voltage value?
What type of signal does the CT or VT output?
Output signals are usually voltage (e g. 0-10V) or current (e.g. 4-20mA). The upper and lower limits of the output signal correspond to specific values on the input side of the CT or VT, with a linear relationship between those limits.
You will need to choose an analog Input module that is capable of reading the output signal from the CT or VT. The user manual for that analog input module will explain how the input signal is represented in the PLC - usually as an integer. You can use that information to convert the integer from the AI module to a floating point value that represents the Voltage or Current measured by the VT or CT.