PLC

Programmable Logic Controllers PLC Analogue card: FX0N-3A

February 16:

· The FX0N-3A analog special function block has two input channels and one output channel. The input channels receive analog signals and convert them into a digital value. This is called an A/D conversion. The output channel takes a digital value and outputs an equivalent analog signal. This is called a D/A conversion. The FX 0N-3A has a maximum resolution of 8 bits.

· The selection of voltage or current based input/output is by user wiring. Analog ranges of 0 to 10V DC (resolution:40mV), 0 to 5V (resolution:20mV) and/or 4 to 20mA (resolution:64 m A) may be selected.

· All data transfers and parameter setups are adjusted through software control of the FX 0N-3A; by use of the TO/FROM applied instructions in the FX0N PC. Communications between the FX 0N PC and FX0N-3A are protected by opto-coupler.

· The FX0N-3A occupies 8 points of I/O on the FX0N’s expansion bus. The 8 points can be allocated from either inputs or outputs.


 * Implications of above:**

The maximum resolution of 8 bits gives us 250 steps at 0 to 5V (which is the proposed voltage input to the temperature sensor circuit). Considering the temperature range we are looking for is between -14 deg and +30 deg, a spread of 45 deg. This would give us approx 5 steps/degree, which means a possible accuracy of 0.2 degrees.

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