PLC PACK for the Colour Maximite 2

After working for a while on the development of the vintage PAL reader for the Color Maximite II micro-computer, I went on to test the PLC type expansion board.

This expansion is equipped with

• - 3 opto-isolated logic inputs.
• - 3 relay outputs
• - 2 analog inputs 10V
• - 1 DS18B20 input
• - 1 TTL serial communication port
• - 1 RS485 serial communication port (optional)

The tests are almost finished :

In this picture, I have connected two control/command screens of different type.

I connected a Nextion screen whose communication takes place by TTL serial link and thanks to a very simple exchange protocol in the form of ASCII frames.

I also connected a second screen which is used in PLC systems and which communicates in Modbus ASCII through an RS485 link. This screen is used to test the control of the outputs of the PLC board.

The program in Basic uses an interrupt to manage the system timer, another interrupt to manage the triggering by the logic inputs of the board and finally a last IRQ for communication with the industrial screen.

Everything works smoothly and very responsively.

I am very impressed by the efficiency of this system, as well as by the basic interpreter which allows to manage without problem all these different interfaces.

The original Colour Maximite 2, an ARM7 based micro-computer :

https://geoffg.net

Soon a more detailed description on https://sillycony.blogspot.com.