Industrial Programmable Logic Controllers : PLC device / add on
pls / plc controlled analog multiplexer / demultiplexer , schematic .
6 x digital channel and 1 x analog channel used by the PLC to make this multiplexer work.
In this example the analog inputs are 4 - 20mA none floating loops. The 1 x analog output to the PLC is 2-10VDC.
74HC/HCT4067 is the 16ch analog multiplexer/demultiplexer circuit used in this example.
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32 channel analog multiplexer
64 channel analog multiplexer made easy . A simple 2bit expander make four 16 channel analog multiplexers work like one 64 channel.
128 channel analog multiplexer made easy
4 - 20 mA current loop .
Interresting examples: AD693 and AD694 from Analog Devices.
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Note! About PLC memory / backup battery.
In this examle this battery is found at the left side of the proccessorboard .
Have the non volatile s-ram with built in lithium battery and other lithium backup batteries replaced before any battery failure . After10 years if ambient battery temperature is less than 40 degrees centigrade . Have the reprogramming ready before you begin this operation .
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