The Mitsubishi Alpha controller is a compact type PLC designed for simple control applications which does not require high speed and many inputs. The controller is equipped with a small LCD screen, on which statements, status of inputs and outputs and configuration settings can be displayed. It has also several keys acting as navigation keys through the controller menu and can also be used in program as additional inputs.
The other property of the keys and screen is possibility to edit the program written into the controller without use of a computer with programming software. The controllers used in the laboratory are Alpha XL type exactly AL2-14MR-D. They have following technical specification:
• 24 VDC power supply
• 14 inputs/outputs connectors:
8 digital inputs, which can be turned programmable into analog inputs with 9 bit resolution and 0-10 V input voltage range
6 relay outputs
• slot for EEPROM or personal computer connection
• wide range expansion modules:
GSM modem connection module
Additional input/output module
AS-I network connection module
Temperature – analog conversion module
The overall Mitsubishi Alpha PLC view, on the example of AL2-24MR-D controller has two controllers. Both controllers have the same appearance, but different input and output numbers.
The Alpha XL controllers, installed in the laboratory are supplied from 24 VDC source. The power can be brought from 230 VAC/24 VDC converters or directly from 24 VDC laboratory mains. There is no risk of electrocution during the experiments because of operating on safe voltage.
Mitsubishi Alpha controllers are programmed in Function Block Diagram (FBD) language. The FBD is a simple representation of real inputs and outputs dependence, thus the program can be also traced and edited directly on controller display. Program has the diagram structure: on the left side the inputs are represented and on the right, the outputs. In order to create a new program the block should be placed between input and output connected by lines.