'C' Functions
You can write C functions directly in the UniLogic editor, or copy and paste code into the C Editor fields.
Use C functions in the same way you use standard ladder functions. You can call them just like standard ladder functions, reuse them, and export/import them via the Library. You can also refer to Ladder functions.
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Note the following limitations:
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Within a C function, all of the declared sub-functions must be static, as well all of the global operands.
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Within a C function, the size of all of the local variables used in that function and its sub-functions must not exceed 256 bytes.
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Float variables are not fully supported. To use floats:
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Your function must use inputs and outputs of the same data type (floats)
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Use functions according to the 'C' Functions Float_Macro table shown at the end of this topic.
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Local float variables and constants must be volatile or cast as volatile float (e.g., STORE(1,(volatile float)0.5,half)). Float function parameters require volatile cast when used as outputs in arithmetic operations.
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Division & Modulo operations: variable divisors are not currently supported. Use these macros instead:
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Instead of "c = a / b;" use: "ARITHMETIC_DIV(1, a, b, c);".
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Instead of "c = a % b;" use: "ARITHMETIC_MOD(1, a, b, c);".
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Global variables are not supported, use static variables instead.
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To create a function, right-click a module and select Add C Function to open the C code editor.
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Your C code must compile correctly in a C compiler.
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The next image shows the Forward Declaration and the Main section of a C function in UniLogic.
Float 'Macro" table
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All inputs and outputs of the function must be of the Float data type.
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b = a
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STORE(1, a, b)
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a > b
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IF_GT(1, a, b)
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a >= b
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IF_GT_EQ(1, a, b)
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a == b
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IF_EQ(1, a, b)
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a != b
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IF_NOT_EQ(1, a, b)
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a <= b
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IF_LT_EQ(1, a, b)
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a < b
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IF_LT(1, a, b)
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c = a + b
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ARITHMETIC_ADD(1, a, b, c)
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c = a - b
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ARITHMETIC_SUB(1, a, b, c)
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c = a * b
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ARITHMETIC_MUL(1, a, b, c)
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c = a / b
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ARITHMETIC_DIV(1, a, b, c)
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++a
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ARITHMETIC_INC(1, a)
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--a
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ARITHMETIC_DEC(1, a)
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b = abs(a)
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ARITHMETIC_ABS(1, a, b)
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b = sqrt(a)
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L_SQRT(1, a, b)
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c = pow(a, b)
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L_POWER(1, a, b, c)
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b = log(a)
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L_LN(1, a, b)
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b = log10(a)
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L_LOG10(1, a, b)
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b = exp(a)
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L_EXP(1, a, b)
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b = sin(a)
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L_SIN(1, a, b)
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b = cos(a)
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L_COS(1, a, b)
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b = tan(a)
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L_TAN(1, a, b)
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b = asin(a)
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L_ASIN(1, a, b)
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b = acos(a)
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L_ACOS(1, a, b)
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b = atan(a)
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L_ATAN(1, a, b)
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b = sinh(a)
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L_SINH(1, a, b)
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b = cosh(a)
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L_COSH(1, a, b)
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b = tanh(a)
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L_TANH(1, a, b)
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Referring to Ladder Functions
In the Properties Window:
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Click Functions References to open the list of Ladder functions in the project.
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Select the desired functions; the C editor displays the references.
Including Used Global Tags
This enables you to view global tags in C functions via online mode, without having to pass them as a parameter.
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Note the following:
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Global variables accessed through the Used Globals feature are implemented as pointers in C functions.
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Required syntax for using global variables:
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In the Properties Window:
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Click Used Globals.
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Begin typing the global name.
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Select the desired globals; click Close.
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In the C function, begin typing the name of the desired tag; click to include it in your code.
Viewing Tag Values in Online Mode
You cannot run Online Mode and work on a C function at the same time.
When you have finished working on a C function, you can enter OnLine Mode and view the value of individual tags, as well as view all of the struct member values. Those available for viewing appear as hyperlinks; simply click the hyperlinks to view the online values.
Viewing Local Tags in OnLine Mode
You can immediately view global tags in online mode. However, in order to view a function's Local tags, you need to first monitor it by right-clicking it in the Ladder that calls the function, and then selecting Monitor as shown in the next image.
