Xylem Expert 7060_7070_Modbus User Manual
Page 28
Communication protocol Serie30
Page 34/37
6.5
Description of the software driver (DLL)
6.5.1 General
The available DLL s30c.dll has been tested on the Windows 95, 98, NT and 2000 operating systems.
Examples of the use of this DLL are available for the following programming languages:
- LabVIEW
- C++
- Delphi
- VB
- VBA
The call convention stdcall is used for assigning the parameters to the functions. This means that:
−
all parameters are passed via the stack,
−
the parameter furthest to the right is calculated and passed first, the parameter furthest to the left is calculated and passed
last,
−
the function itself deletes the parameters from the stack.
As the declarations for the functions presented below show, many variables are declared with the prefixed word var. This means
that these variables are passed as pointers and not as values.
The types employed for declaration purposes are described below:
Type
Range
Format
Byte
0..255
8-bit without sign
Word
0..65535
16-bit without sign
Smallint
-32768..32767
16-bit with sign
Longint
-2147483648.. 2147483647
32-bit with sign
Pbyte
Pointer to byte
Single
+/- 1.5x10
-45
..3.4x10
38
32-bit
6.5.2 The functions of the DLL
Each function returns a value which indicates whether the desired function has been successfully executed or not. All the
possible return values are specified below. The returned parameters are only valid and may only be processed if the function
concerned has been successfully executed.
Return value
Description
RS_OK
0
Function successfully executed; return parameters are valid
RS_EX1
1
Function successfully executed; but exception error 1 has occurred
RS_EX2
2
Function successfully executed; but exception error 2 has occurred
RS_EX3
3
Function successfully executed; but exception error 3 has occurred
RS_EX32
32
Function successfully executed; but exception error 32 has occurred
RS_BROADCAST 100 Broadcast
RS_ERROR
-1
General error
RS_TXERROR
-2
Transmit error
RS_RXERROR
-3
Receive error in UART
RS_TIMEOUT
-4
No data or insufficient data received
RS_BADDATA
-5
Data erroneous (e.g. CRC16 erroneous)