Let’s study the working of **converter instruction** in Siemens **PLC** programming using different ladder logics and programs.

## Converter Instruction in PLC

## Block Description

### Round to double integer:

It reads the input floating point value and converts it to double integer and round to nearest integer. The result is output by the parameter OUT.

### Truncate double integer part:

It reads the input floating point value and converts it to double integer and round to zero mode. The result is output by the parameter OUT.

### Ceiling:

It reads the input floating point value and converts it to double integer. The result is the lowest integer which is greater than the floating point number i.e Round to + infinity mode. The result is output by the parameter OUT.

### Floor:

It reads the input floating point value and converts it to double integer. The result is the greatest integer component which is greater than the floating point number i.e Round to -infinity mode. The result is output by the parameter OUT.

## Ladder Logic

### Ladder Description:

#### Network 1:

If I0.0 is pressed, value in MD0 (99.78) is read as a floating point number and converted to the closest double integer(100). The result of round to integer is stored in MD4(100).

#### Network 2:

If I0.0 is pressed, value in MD0 (99.78) is read as a floating point number and converted to the double integer. The integer part of the floating point number is the result. The result is stored in MD12 (99).

#### Network 3:

If I0.0 is pressed, value in MD0 (99.78) is read as a floating point number and converted to the double integer by round function . The result is stored in MD12 (100).

#### Network 4:

If I0.0 is pressed, value in MD0 (99.78)is read as a floating point number and converted to the double integer by the round to – infinity mode. The result is stored in MD16(99).

Note: For positive numbers, trunc and floor give the same result. But for negative numbers, floor rounds down and trunc rounds up. This is because trunc always rounds toward 0.

Author: Hema Sundaresan

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