S7 OPC Items

Owned by Michael Standal
Last updated: Jun 30, 2020
3 min read

Standard Items

See Device Standard Items.

PLC Inputs

ItemData TypeDescription

IB[0ffset]

UI1

Input Byte. Reads a single Byte starting with the offset specified. 

Example: IB1, Read the Input Byte starting at offset 1.

IX[Offset].[0-7]

BOOLEAN

Input boolean. Reads a single bit index from the offset specified. 

Example: IX1.0, Read the Input bit in the first (0) position starting at offset 1.

IW[Offset]

UI2

Input WORD. Reads two consecutive bytes as a WORD starting from the offset specified. 

Example: IW2, Read the two-byte WORD starting at offset 2.

II[Offset]I2

Input Integer. Reads two consecutive bytes as a Singed Integer starting from the offset specified. 

Example: II2, Read the two-byte Int starting at offset 2.

ID[Offset]

UI4

Input DWORD. Reads four consecutive bytes as a DWORD starting from the offset specified. 

Example: ID2, Read the four-byte DWORD starting at offset 2.

IR[Offset]

R4

 Input REAL. Reads four consecutive bytes as a REAL number starting from the offset specified. 

Example: IR2, Read the four-byte REAL starting at offset 2.

PLC Outputs

ItemData TypeDescription

OB[0ffset]

UI1

Output Byte. Reads a single Byte starting with the offset specified. 

Example: OB1, Read the Output Byte starting at offset 1.

OX[Offset].[0-7]

BOOLEAN

Output boolean. Reads a single bit index from the offset specified. 

Example: OX1.0, Read the Output bit in the first (0) position starting at offset 1.

OW[Offset]

UI2

Output WORD. Reads two consecutive bytes as a WORD starting from the offset specified. 

Example: OW2, Read the two-byte WORD starting at offset 2.

OI[Offset]I2

Output Integer. Reads two consecutive bytes as a Singed Integer starting from the offset specified. 

Example: OI2, Read the two-byte Int starting at offset 2.

OD[Offset]

UI4

Output DWORD. Reads four consecutive bytes as a DWORD starting from the offset specified. 

Example: OD2, Read the four-byte DWORD starting at offset 2.

OR[Offset]

R4

 Output REAL. Reads four consecutive bytes as a REAL number starting from the offset specified. 

Example: OR2, Read the four-byte REAL starting at offset 2.

PLC Merker Memory

ItemData TypeDescription

MB[0ffset]

UI1

Merker Byte. Reads a single Byte starting with the offset specified. 

Example: MB1, Read the Merker Byte starting at offset 1.

MX[Offset].[0-7]

BOOLEAN

Merker boolean. Reads a single bit index from the offset specified. 

Example: MX1.0, Read the Merker bit in the first (0) position starting at offset 1.

MW[Offset]

UI2

Merker WORD. Reads two consecutive bytes as a WORD starting from the offset specified. 

Example: MW2, Read the two-byte WORD starting at offset 2.

MI[Offset]I2

Merker Integer. Reads two consecutive bytes as a Singed Integer starting from the offset specified. 

Example: MI2, Read the two-byte Int starting at offset 2.

MD[Offset]

UI4

Merker DWORD. Reads four consecutive bytes as a DWORD starting from the offset specified. 

Example: MD2, Read the four-byte DWORD starting at offset 2.

MR[Offset]

R4

Merker REAL. Reads four consecutive bytes as a REAL number starting from the offset specified. 

Example: MR2, Read the four-byte REAL starting at offset 2.

PLC Data Blocks

ItemData TypeDescription

DB[BlockNum]:B[0ffset]

UI1

Data block Byte. Reads a single Byte starting with the offset specified. 

Example: DB1:B1, Read the Data Block Byte starting at offset 1 of Data Block number 1.

DB[BlockNum]:X[Offset].[0-7]

BOOLEAN

Data block boolean. Reads a single bit index from the offset specified. 

Example: DB1:X1.0, Read the Data block bit in the first (0) position starting at offset 1 of Data Block  number 1.

DB[BlockNum]:W[Offset]

UI2

Data block WORD. Reads two consecutive bytes as a WORD starting from the offset specified. 

Example: DB1:W2, Read the two-byte WORD starting at offset 2 of Data Block number 1.

DB[BlockNum]:I[Offset]I2

Data block Integer. Reads two consecutive bytes as a Singed Integer starting from the offset specified. 

Example: DB1:I2, Read the two-byte Integer starting at offset 2 of Data Block number 1.

DB[BlockNum]:D[Offset]

UI4

Data block DWORD. Reads four consecutive bytes as a DWORD starting from the offset specified. 

Example: DB1:D2, Read the four-byte DWORD starting at offset 2 of Data Block number 1.

DB[BlockNum]:R[Offset]

R4

 Data block REAL. Reads four consecutive bytes as a REAL number starting from the offset specified.  Example: DB1:R2, Read the four-byte REAL starting at offset 2 of Data Block number 1.

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