S7 Item Syntax

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The S7 item syntax is set up as shown below:

<Area><Data type><Start address>[.Array size][Suffix]

 

If the data type is BOOL, the bit number is required:

<Area><Data type><Start address><.Bit number>[.Array size]

 

If the data type is STRING, the string length is required:

<Area><Data type><Start address><.String length>[.Array size][Suffix]

Legend: <> mandatory        [ ] optional

<Area>

 

Syntax

Orientation1

Access Rights

Notes

Data block

DBx.

V synonym for DB1

BYTE

Read / write

With data blocks, the specification of a block number x is required (x = 1 to 65535). A dot must appear after the block number.

Instance block

DIx.

BYTE

Read / write

Flag

M or F

BYTE

Read / write


Timer

T

WORD

Read

directly followed by the timer number.

The data type is REAL, with suffix S5T STRING

Counter

Z or C

WORD

Read / write

directly followed by the counter number.

Input

E or I

BYTE

Read


Output

A or O or Q

BYTE

Read / write


I/O Input

PE or PI

BYTE

Read


I/O Output

PA or PO or PQ

BYTE

Read / write


1BYTE-oriented means that a byte is addressed for each physical address.

WORD-oriented means that a word (16 bits) is addressed for each physical address.

<Data type>

Type

Syntax

DB / DI

M

I/O

PI /PO

C/T

with Array

useful

Suffixes

BIT

VT_BOOL

X

DB5.X4.3

MX1.3

---

---

---

---

---

BIT

VT_BOOL

 

DB5.4.3

M1.3

E4.3

I4.3

A4.3

O4.3

PE4.5

PI4.5

PA1.3

PO1.3

---

---

---

BYTE

VT_UI1

B

Byte

DB5.B2

DB5.Byte2

MB4

MByte4

FB4

FByte4

EB4

EByte4

IB4

IByte4

AB5

AByte5

OB5

OByte5

PEB4

PEByte4

PIB4

PIByte4

PAB5

PAByte5

POB5

POByte5

---

DB5.B2.4

DB5.Byte2.4

MB4.3

MByte4.3

FB4.4

FByte4.4

POB5.3

etc.

KF

BCD

WORD

VT_UI2

VT_I4*

W

Word

DB5.W3

DB5.Word3

MW4

MWord4

FW4

FWord4

EW4

EWord4

IW4

IWord4

AW5

AWord5

OW5

OWord5

QWord5

PEW4

PEWord4

PIW4

PIWord4

PAWord5

PAWord5

POW5

POWord5

C5

Z5

T5

DB5.W3.2

DB5.Word3.2

MW4.2

EWord4.2

PAWord5.3

C5.3

Z5.10

T5.2

etc.

KF

BCD

KT

S5T

TR

D

SWAP

INT

VT_I2

I

Int

DB5.I3

DB5.Int3

MI4

MInt4

FI4

FInt4

EI4

EInt4

II4

IInt4

AI5

AInt5

OI5

OInt5

PEI4

PEInt4

PII4

PIInt4

PAI5

PAInt5

POI5

POInt5

---

DB5.I3.2

DB5.Int3.2

MI4.4

FInt4.3

AInt5.3

OI5.2

OInt5.5

POInt5.4

etc.

SWAP

REAL

VT_R4

R

Real

DB5.R2

DB5.REAL2

MR4

MREAL4

ER4

EREAL4

IR4

IREAL4

AR4

AREAL4

OR4

OREAL4

PER4

PEREAL4

PIR4

PIREAL4

PAR4

PAREAL4

POR4

POREAL4

----

DB5.R2.2

DB5.REAL2.4

MR4.5

ER4.4

AREAL4.5

PER4.2

PAR4.7

POR4.3

etc.

KG

SWAP

STRING

VT_BSTR

S

String

DB5.S1.80

DB5.String1.80

MS2.80

MString2.80

---

---

---

DB5.S1.80.5

DB5.String1.80.5

MS2.80.3

MString2.80.3

KA1

S7-STRING

VT_BSTR

G

SS

DB5.G2.80

DB5.SS2.80

MG2.80

MSS2.80

---

---

---

DB5.G2.80.5

DB5.SS2.80.5

MG2.80.5

MSS2.80.5

---

S5-STRING

VT_BSTR

SF

DB5.SF2.80

FSF2.80

---

---

---

DB5.SF2.80.5

MSF2.80.5

---

DOUBLE WORD

VT_UI4

VT_R8*

 

DW

Dword

DB5.DW3

DB5.Dword3

MDW4

MDWord4

FDW4

FDWord4

EDW4

EDWord4

IDW4

IDWord4

ADW5

ADWord5

ODW5

ODWord5

QDW5

PEDW4

PEDWord4

PIDW4

PIDWord4

PADW5

PADWord5

PODW5

PODWord5

---

DB5.DW3

MDW4.2

FDW4.2

EDW4.4

ADWord5.8

PEDW4.8

PADW5.4

PODW5.4

etc.

KF

BCD

KG

T

TOD

SWAP

DOUBLE INT

VT_I4

D

DI

DInt

DB5.D3 2

DB5.DI3

DB5.DInt3

MDI4

MDInt4

FDI4

FDInt4

EDI4

EDInt4

IDI4

IDInt4

ADI5

ADInt5

ODI5

ODInt5

QDI5

PEDI4

PEDInt4

PIDI4

PIDInt4

PADI5

PADInt5

PODI5

PODInt5

---

DB5.D3.2

DB5.DI3.2

DB5.DInt3.4

MDI4.5

EDI4.5

ADI5.2

PEDI4.5

PADInt5.2

etc.

BCD

T

TOD

SWAP

QUAD WORD

VT_UI8

QW

Qword

DB5.QW3

DB5.Qword3

MQW4

MQWord4

FQW4

FQWord4

EQW4

EQWord4

IQW4

IQWord4

AQW5

AQWord5

OQW5

OQWord5

QQW5

PEQW4

PEQWord4

PIQW4

PIQWord4

PAQW5

PAQWord5

POQW5

POQWord5

---

DB5.QW3

MQW4.2

FQW4.2

EQW4.4

AQWord5.8

PEQW4.8

PAQW5.4

POQW5.4

etc.

KF

BCD

SWAP

QUAD INT

VT_I8

Q

QI

QInt

DB5.Q3

DB5.QI3

DB5.QInt3

MQI4

MQInt4

FQI4

FQInt4

EQI4

EQInt4

IQI4

IQInt4

AQI5

AQInt5

OQI5

OQInt5

QQI5

PEQI4

PEQInt4

PIQI4

PIQInt4

PAQI5

PAQInt5

POQI5

POQInt5

---

DB5.Q3.2

DB5.QI3.2

DB5.QInt3.4

MQI4.5

EQI4.5

AQI5.2

PEQI4.5

PAQInt5.2

etc.

SWAP

DOUBLE

VT_R8

QR

QReal

DB5.QR2

DB5.QREAL2

MQR4

MQREAL4

EQR4

EQREAL4

IQR4

IQREAL4

AQR4

AQREAL4

OQR4

OQREAL4

PEQR4

PEQREAL4

PIQR4

PIQREAL4

PAQR4

PAQREAL4

POQR4

POQREAL4

----

DB5.QR2.2

DB5.QREAL2.4

MQR4.5

EQR4.4

AQREAL4.5

PEQR4.2

PAQR4.7

POQR4.3

etc.

SWAP

Date and Time

VT_DATE

DT

DB5.DT3

MDT4

EDT4

IDT4

ADT5

ODT5

QDI5

PEDT4

PIDT4

PADT5

PODT5

---

DB5.DT3.2

MDT4.2

EDT4.2

PEDT4.2

etc.

ISO

1  KA Suffix is not possible with string arrays

2  Caution! Danger of mix up with S5 syntax for bit (DB5D1.1)

 

Notes on counters and timers

Counters and timers are always addressed by words. For this reason, the specification of a data type is not required!

The start address directly follows the “T” or “C/Z” area. Timers can only be read! Counters can be read and written.

Timer values are indicated in seconds (e.g., T = 0.7 => T = 0.7 s = 700 ms).

Counters are represented in decimals (0 to 999).

<Start address>

The start address specifies the addresses starting at which can be read or written.

Example: DB5.DW6: Double word 6 of the data block 5 is the start address.

Example: MB17: Flag byte 17 is the start address.

If the start address is a certain bit, the bit number must also be specified.

<.Bit number>

The bit number must always be specified when the data type is BOOL.

Example: I4.3: bit 3 of input byte 4 – an input bit is addressed here.

Example: MX12.1: Bit 1 of flag byte 12 – a flag bit is addressed here.

[.Array size]

An array (i.e., field, row, data area) is a series of equal elements. An array combines several units of one data type into a field. If, for example, several words are read out from a data block, this is called an array of words. To create an array, the length of the array is added to the standard syntax separated by a dot.

Example: DB10.REAL2.5.

For more information on arrays, see also Arrays.

[Suffix]

A value can be represented in another format with the aid of a suffix.

For more information on suffixes, see also Suffixes.