PLC (AB SLC 500) Data Masking -- Introduction to masking using an SQO sequencer block

The purpose of this animation is to illustrate how masking is accomplished with PLC instructions. We will start our examination of the process of masking by looking at the two input AND gate and how it operates.

The MVM (Masked Move), the SQC (Sequencer Compare), SQO (Sequencer Output) instructions all use this masking technique to control or filter data selection. The mask value is shown in hexadecimal format as denoted by the letter h. Note that each hex digit has a 4 bit binary representation. Therefore a four digit hex mask value represents 16 binary bits.

In short, the MASK is a 16 bit hexadecimal number through which SQO instruction moves data. When MASK bit is set (i.e. binary 1) the data is passed and when MASK bit is reset (i.e. binary 0), the data is masked (blocked).

By modifying the mask value, we can selectively send parts of a data word to a desired output. This masking technique is widely used in PLC applications.

The AND gate used in this example has two inputs, A and B, and a single output Z. Along with the symbol for the AND gate, we have the Truth Table which describes the behaviour of the Z output with respect to the A and B inputs. The truth Table provides the gate output state for all possible combinations appearing at the A and B inputs. The only time at which the Z output is in the 1 state, is when inputs A and B are both in the 1 state. If either A or B is in the 0 state, the Z output will be 0. Masking uses this "AND" function to pass or block selected bits of an input or output word. Some PLC ladder logic instructions utilize this masking technique to treat data selectively.

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Thanks for making and sharing this video!

[Mukesh-]

hello sir B3:1 1100101100111010 WHERE THESE VALUES COME FROM PLZ HELP