S7-SoftPLC:Data Interface
Contents
Data interface to S7-SoftPLC
S7-SoftPLC can be accessed directly by various high level languages (e.g. Visual Basic®, Visual C/C++® or Borland C++Builder®). The DLL required for this (PLC32.DLL) is installed with S7-SoftPLC. The PLC32.DLL is a 32 Bit application.
Below the available functions for a data exchange are described.
Data transmitting functions
Read a single value
Reads a value from S7-SoftPLC.
| unsigned long int DLLexport ReadVal | (unsigned long int type, |
| unsigned long int no, | |
| unsigned long int DBNo, | |
| unsigned long int size, | |
| unsigned long int far * val);, |
| Parameter | Description | Comment |
|---|---|---|
| type | 'I' = input 'Q' = output 'M' = flag 'C' = counter value 'T' = timer value 'D' = data word or double data word 'B' = data bit, word, double word on byte address 'P' = P_Parameter |
16-bit-access only 16-bit-access only depending on size depending on size compatible to S7 only S7 from version 3 only |
| no | adress | Byte address of read in operand |
| DBNo | Number of data block | 1 – 16383 |
| size | Number of bits 0..7= bit no 0 7 8 = 1 byte 16 = 1 word 32 = 1 double word |
'I','Q','M' only |
| val | Read value | Pointer to a valid variable in the user applications address space |
| return | 0 on Error | Error messages |
Length of parameter list (Visual-C): 20 bytes.
Write a single value
Writes a value in S7-SoftPLC.
| unsigned long int DLLexport WriteVal | (unsigned long int type, |
| unsigned long int no, | |
| unsigned long int DBNo, | |
| unsigned long int size, | |
| unsigned long int far * val);, |
| Parameter | Description | comment |
|---|---|---|
| type | 'I' = input 'Q' = output 'M' = flag 'C' = counter value 'T' = timer value 'D' = data word or double data word 'B' = data bit, byte, wort, doppelwort on byte address 'P' = P_Parameter |
16-bit-access only 16-bit-access only depending on size depending on size compatible to S7 only S7 from version 3 only! |
| no | adress | Byte address of operand to be written |
| DBNo | number of data block | 1 – 16383 |
| size | number of bits 0..7= bit no 0 7 8 = 1 byte 16 = 1 word 32 = 1 double word |
'I','Q','M' only |
| val | value to be written | |
| return | 0 on error | Error messages |
Length of parameter list (Visual-C): 20 bytes.
Read multiple values
Reads multiple values from S7-SoftPLC.
| unsigned long int DLLexport ReadVals | (unsigned long int type, |
| unsigned long int no, | |
| unsigned long int DBNo, | |
| unsigned long int size, | |
| unsigned long int far * vals);, |
| Parameter | Description | Comment |
|---|---|---|
| type | 'I' = input 'Q' = output 'M' = flag 'D' = data word 'B' = data byte on byte address |
S5 compatible compatible to S7 only |
| no | adress | |
| DBNo | number of data block | 1 – 16383 |
| size | number of data bytes or data words | destination size in bytes for type 'I', 'Q', 'M' and 'B', destination size in data words for 'D' |
| vals | Value of byte | Pointer to a valid array in the user applications address space
Warning: Array has to be big enough! |
| return | 0 on error | Error messages |
Length of parameter list (Visual-C): 20 bytes.
WARNING: FOR DATA BLOCKS (TYPE 'D') THE ARRAY HAS TO BE TWICE AS BIG, SINCE 2 BYTES ARE NECESSARY FOR EVERY DATA WORD!
Write multiple values
Writes multiple values to S7-SoftPLC.
| unsigned long int DLLexport WriteVals | (unsigned long int type, |
| unsigned long int no, | |
| unsigned long int DBNo, | |
| unsigned long int size, | |
| unsigned long int far * vals);, |
| Parameter | Description | Comment |
|---|---|---|
| type | 'I' = input 'Q' = output 'M' = flag 'D' = data word 'B' = data byte on byte address |
S5 compatible compatible to S7 only |
| no | adress | |
| DBNo | number of data block | 1 – 16383 |
| size | number of data bytes or data words 'I' 'Q' 'M' 'B' 'D' |
Destination size in bytes Destination size in bytes Destination size in bytes Destination size in bytes Destination size in data words |
| vals | value of byte | Pointer to a valid array in the user applications address space
Warning: Array has to be big enough! |
| return | 0 on error | Error messages |
Length of parameter list (Visual-C): 20 bytes.
WARNING: FOR DATA BLOCKS (TYPE = D) THE ARRAY HAS TO BE TWICE AS BIG, SINCE 2 BYTES ARE NECESSARY FOR EVERY DATA WORD!
Read DB
Reads the content of a data block from S7-SoftPLC.
| unsigned long int DLLexport ReadDB | (unsigned long int no, |
| unsigned short int far * block, | |
| unsigned long int far * size, | |
| unsigned long int synchronous); |
| Parameter | Description | Comment |
|---|---|---|
| no | number of data block | 1..16383 |
| block | pointer to data block content | Pointer to a valid array in the user applications address space.
Warning: Array has to be big enough! |
| size | number of words that are to be read from the data block | If the data block is smaller than the size, the size will be reduced automatically.
Pointer to a valid variable in the user applications address space. |
| synchronous | always 0 | irrelevant for S7 |
| return | 0 on error | Error messages |
Length of parameter list (Visual-C): 16 bytes.
WARNING: WORD-ORIENTED READING, LOW- AND HIGH-BYTE ARE SWAPPED.
Write DB
Writes a data block to S7-SoftPLC.
| unsigned long int DLLexport WriteDB | (unsigned long int no, |
| unsigned short int far * block, | |
| unsigned long int far * size, | |
| unsigned long int synchronous); |
| Parameter | Description | Comment |
|---|---|---|
| no | number of data block | 1..16383 |
| block | pointer to data block content | Pointer to a valid array in the user applications address space
Warning: Array has to be big enough! |
| size | number of words that are to be written into the block | If the data block is smaller than the size, the size will be reduced automatically.
Pointer to a valid variable in the user applications address space. |
| synchronous | always 0 | irrelevant for S7 |
| return | 0 on error | Error messages |
Length of parameter list (Visual-C): 16 bytes.
WARNING: WORD-ORIENTED READING, LOW- AND HIGH-BYTE ARE SWAPPED.
Read S7 DB
Reads the content of a S7 data block from the PLC (byte oriented).
| unsigned long int DLLexport ReadDB_S7 | (unsigned long int no, |
| unsigned char int far * block, | |
| unsigned long int far * size, |
| Parameter | Description | Comment |
|---|---|---|
| no | number of data block | 1..16383 |
| block | pointer to data block content | Pointer to a valid array in the user applications address space
Warning: Array has to be big enough! |
| size | number of bytes that are to be read into the block | If the data block is smaller than the size, the size will be reduced automatically.
Pointer to a valid variable in the user applications address space. |
| return | 0 on error | Error messages |
Length of parameter list (Visual-C): 12 bytes.
Write S7 DB
Writes the content of a S7 data block in the PLC (byte-oriented).
| unsigned long int DLLexport WriteDB_S7 | (unsigned long int no, |
| unsigned char int far * block, | |
| unsigned long int far * size, |
| Parameter | Description | Comment |
|---|---|---|
| no | number of data block | 1..16383 |
| block | pointer to data block content | Pointer to a valid array in the user applications address space
Warning: Array has to be big enough! |
| size | number of bytes that are to be written into the block | If the data block is smaller than the size, the size will be reduced automatically.
Pointer to a valid variable in the user applications address space. |
| return | 0 on error | Error messages |
Length of parameter list (Visual-C): 12 bytes.
Functions for data conversion
FloatToMC5
Converts floating point numbers from IBM-PC-format into S7 double words.
| void DLLexport FloatToMC5 | (float FloatValue, |
| unsigned long far * MC5Val); |
| Parameter | Description | Comment |
|---|---|---|
| FloatVal | floating point number in IEEE- or INTEL-format | |
| MC5Val | floating point number in Siemens-S7-format |
MC5ToFloat
Converts S7 double words into floating point numbers in IBM-PC-format.
| void DLLexport MC5ToFloat | (unsigned long far * MC5Val |
| float FloatVal); |
| Parameter | Description | Comment |
|---|---|---|
| MC5Val | floating point number in Siemens-S7-format | |
| FloatVal | floating point number in IEEE- or INTEL-format |
Accessing with a web server
If you are intending to access S7-SoftPLC with web applications(IIS), which should have access to the process data, please contact our support for examples. The S7-SoftPLC installs an object, which allows data access from script languages (VB Sript, J Script).
