GATHER: Merge individual bits into a bit sequence (S7-1200, S7-1500) - STEP 7

Description

The "Merge individual bits into a bit sequence" instruction merges the bits from an ARRAY of BOOL, an anonymous STRUCT or a PLC data type exclusively with Boolean elements into a bit sequence. The bit sequence is saved in a tag of the data type BYTE, WORD, DWORD or LWORD.

Note Multi-dimensional ARRAY of BOOL With the "Merge individual bits into a bit sequence" instruction, the use of a multidimensional ARRAY of BOOL is not permitted.

Note Length of the ARRAY, STRUCT or PLC data type The ARRAY, STRUCT or the PLC data type must have exactly the number of elements that is specified by the bit sequence. This means for the data type BYTE, for example, the ARRAY, anonymous STRUCT or the PLC data type must have exactly 8 elements (WORD = 16, DWORD = 32 and LWORD = 64).

Note Availability of the instruction The instruction can be used with a CPU of the S7-1200 series as of firmware version >4.2, and for a CPU of the S7-1500 series as of firmware version 2.1.

The enable output ENO returns signal state "0" if one of the following conditions applies:

• Enable input EN has signal state "0".

• The ARRAY, anonymous STRUCT or the PLC data type (UDT) has fewer or more BOOL elements than specified by the bit sequence. In this case the BOOL elements are not transferred.

• Fewer than the necessary number of bits are available.

Parameter

The following table shows the parameters of the instruction:

You can select the required bit sequence from the "???" drop-down list of the instruction box.

You can find additional information on valid data types under "See also".

Example with an ARRAY

Create the following tags in the block interface:

The following example shows how the instruction works:

The following table shows how the instruction works using specific operand values:

If the operand #Enable returns the signal state "1" at the enable input EN, the instruction is executed. The bits of the #SourceArray operand are merged into a WORD. If an error occurs during the execution of the instruction, the operand #EnableOut returns the signal state "0" at the enable output ENO.

Example with a PLC data type (UDT)

Create the following PLC data type "myBits":

Create the following tags in the block interface:

The following example shows how the instruction works:

The following table shows how the instruction works using specific operand values:

If the operand #Enable returns the signal state "1" at the enable input EN, the instruction is executed. The bits of the #SourceUDT operand are merged into a WORD. If an error occurs during the execution of the instruction, the operand #EnableOut returns the signal state "0" at the enable output ENO.