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Setting up the Analog Input Card in RSLogix 5000

Let’s assume that the output of our scales has been calibrated for 0-10 VDC. Zero volts equals 0 pounds, and 10 volts equals 2000 pounds.

Now we know the signal type is DC voltage, the range is 0-10 and the engineering units are pounds.

Right-click on the 1756-IF8 card in the Controller Organizer and choose “Properties”. Click on the “Configuration” tab and you will see this. Continue reading Setting up the Analog Input Card in RSLogix 5000

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Equivalent Logic in PLC Programming

If you understand basic electrical diagrams, it is much easier to understand ladder logic.

In fact, that was the whole idea behind ladder logic. It was supposed to look, and work, like real electrical circuits

Excerpted from “The Beginner’s Guide to PLC Programming”

In its elementary form, PLC logic is very similar to the hard-wired logic you would find in an electrical ladder diagram.

For example, if you wanted to turn on a light with a momentary pushbutton, you would wire it like the circuit below.

Continue reading Equivalent Logic in PLC Programming

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Setting up the Analog Input Card in RSLogix 5000

Let’s assume that the output of our scales has been calibrated for 0-10 VDC. Zero volts equals 0 pounds, and 10 volts equals 2000 pounds.

Now we know the signal type is DC voltage, the range is 0-10 and the engineering units are pounds.

Right-click on the 1756-IF8 card in the Controller Organizer and choose “Properties”. Click on the “Configuration” tab and you will see this.

Continue reading Setting up the Analog Input Card in RSLogix 5000

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Addressing in RSLogix 5000

Before you can program any PLC system, you have to understand how the addressing is done in that particular PLC. I have included a actual screenshot from RSLogix 5000 below that shows examples of addressing in RSLogix 5000.

INSTRUCTION – RSLogix 5000’s Relay Ladder Logic command language is comprised of “instructions”. An XIC (it looks like a normally open contact –] [– ) is an instruction. A timer is an instruction. A few of the most common instructions are described below.

BIT – an address within the PLC. It can be an input, output or internal coil, among others.

RUNG – A section of the PLC ladder program that terminates in an output function of some type. Just like in an electrical ladder diagram, a rung has some type of output that is turned on or turned off by the preceding entities in the rung. The first rung in a ladder program is always 0.

HARDWIRED INPUT – a physical connection to the PLC from an input device (switch or sensor, etc.).

RSLogix 5000 defines the address of the input, based on the input cards that you configure.

We’ll see how this works later on, but here is an example of a hardwired input:

Local:4:I.Data.3

Continue reading Addressing in RSLogix 5000