# FC 112 - Ladder Logic Rung (20 Input)

Function code 112 implements a rung of a Ladder logic program (relay type). It accepts 20 boolean input signals and performs a fundamental operation on each input in sequential order. After each input is operated on, the resulting value goes to the top of the stack. The output of the rung block is the value on the top of the stack unless S1 forces it to another value. Outputs:

 Blk Type Description N R Output value determined by S1 and value on top of stack If S1 = 0, output = value on top of stack If S1 = 1, output = previous value of output If S1 = 2, output = logic 0 If S1 = 3, output = logic 1

Specifications:

NOTES:

1. Maximum values are: 9,998 for the BRC-100 , IMMFP11/12 and 31,998 for the HAC

112.1   Explanation

This block accepts 20 boolean inputs, performs a specified fundamental operation on each input in turn, and provides an output dependent on the results of the operations and the output mode selected with S1.

The controller takes a Ladder program entered on a human system interface (HSI) and translates it to a group of rung

blocks internally. Any changes made to the Ladder program after the conversion are easily saved by downloading them to the controller. This insures that all information is in the proper format when it is processed.

The function code the rung is translated to depends on the number of inputs to the rung. This is automatically defined in the Harmony controllers by the PC90 Ladder programmer. Figures 110-1 and 110-2 illustrate how to use the rung function codes (110, 111, 112) without the PC90 Ladder programmer.

AND, OR and PUT operations are performed sequentially on inputs one through 20 as specified with S2 through S21. The PUT operation places the specified value on top of a stack of values. The result of the most current operation always goes to the top of the stack. The value resulting from operation one is placed on a stack that has an initial value of one in the harmony controllers. Operation two is then performed, and the resulting value becomes the value on top of the stack, and so on through operation five. Once all operations have been performed, the controller reads S1 to determine the output value. If it is zero, the value from the top of the stack (the result of operation 20) is the output. Otherwise, the output is overridden and forced to zero or one or held from the previous output. The value on the top of the stack reverts to the initial value at the beginning of each controller execution cycle, so the first operation should always be a PUT to insure that the operations are performed on the desired values.

112.1.1  Specifications

S1 - OUT

(Output descriptor) Defines the output:

0 = Normal output. The value of the output will be the value on top of the stack when all operations on inputs are complete.

1 = Hold previous output. The value of the output will be the previous output value, regardless of the value on top of the stack.

2 = Force output to logic 0. The value of the output will be logic 0 regardless of the value on top of the stack.

3 = Force output to logic 1. The value of the output will be logic 1 regardless of the value on top of the stack.

S2 to S21 - F1 to F20

Identify:

1. The operation to be performed on the input.

2. The input value the operation is performed on.

3. The input override.

Specification information for S2 through S21 is in the format: S12 to S21- IN1 to IN20

Block addresses of inputs one through five.

111.1.2  Outputs

N

Dependent on value on top of the stack and the value of S1.

• If S1 = 0, output = value on top of the stack.

• If S1 = 1, output = previous value of output, regardless of the value on top of the stack.

• If S1 = 2, output = logic 0, regardless of the value on top of the stack.

• If S1 = 3, output = logic 1, regardless of the value on top of the stack.

111.2   Applications

Refer to the example in function code 110.