Chapter 5 Understanding Common Devices class. In a ladder diagram, OUTPUTs are put at the right sides of function blocks with pins sending the operation results to the caller. INOUT － Symbol used as a feedback pin of a function block A symbol of this class is used as a feedback pin of a function block. It can only be declared in the function block. Please refer to the following example. When the function block is called, the caller sends the value in D1 to DT_IO, which is a symbol of the INOUT class. After the operation comes to an end, the final value of DT_IO is sent to D1. In a ladder diagram, the symbols of this class are put at the left sides of function blocks.
5.4.3 Data Types The data type of a symbol determines the format of the value of the symbol. Suppose there are two symbols VAR_1 and VAR_2. The data type of VAR_1 is BOOL, and the data type of VAR_2 is WORD. If VAR_1 and VAR_2 are used in a program, VAR_1 will represent a contact, and VAR_1 will represent a 16-bit device which can be involved in arithmetic operation or transferring the data. The data types supported by ISPSoft are listed below. 5_ 5-17 Function Data type Name Description Program block BOOL Boolean A Boolean value represents the state of a contact, could be TRUE or FALSE. WORD Word Bit string of length 16. DWORD Double Word Bit string of length 32.
LWORD Long Word Bit string of length 64. UINT Unsigned integer 16-bit data. UDINT Unsigned double integer 32-bit data. INT Integer 16-bit data DINT Double integer 32-bit data. LINT Long Integer 64-bit data. REAL Real numbers 32-bit data; applicable to single precision floating-point instructions. LREAL Long reals 64-bit data; applicable to double precision floating-point instructions. CNT Counter 16-bit counter value or 32-bit counter value. TMR Timer 16-bit timer value.