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The following public member functions are provided as part of the tpriModPlc class:

• tpriModPlc *pModPlc = new tpriModPlc;

Allocate a new tpriModPlc object

• destroy (tpriModPlc *)pModPlc();

Destroy the tpriModPlc class object.

• int SetTraceLevel (int TraceLevel);

where:

int TraceLevel = debug trace level for class operations

                           default value = 30

                           valid values range between 0 and 100, inclusive

                           lower values produce less debug information

                           higher values produce more debug information

                           debug information written using LogMsg function

This function stores a new value for the TraceLevel parameter

• int SetTimeOut (int sTimeOut, int rTimeOut, unsigned char ticktime,

                              unsigned char timeoutticks, unsigned char timeoutmultiplier,

                              unsigned long otrpi, unsigned long torpi );

where:

int sTimeOut = Send message timeout value in milliseconds

                                    Default value = 2000

int rTimeOut = receive message timeout value in milliseconds

                                    Default value = 2000

This function stores timeout parameter values for use by the member functions of the class

• int int SetDestinationInfo(unsigned char destID);

where:

unsigned short vendorid = Destination ID

default value = 1

This function stores new values for the Destination ID

• int SetPduMaxIoDataBytes (int noBytes);

where:

int noBytes = the maximum number of data bytes that will be placed in a single PDU

                           default value = 125

                           a PDU is a protocol Data Unit and is equivalent to a single Ethernet frame   

                           valid values range between 2 and 125, inclusive

                           lower values may produce more frames to transfer the same user data

                           higher values may produce fewer frames to transfer the same user data

This function sets a new value for the maximum number of user data bytes to be included in a single Ethernet frame (PDU) that is transmitted to the PLC.  A value too low will increase the number of Ethernet frames that will be required to send a given number of user data bytes and reduce throughput. A number too high will not be understood or acknowledged by the PLC.  

• int Connect (char *hostname, short int port);

where:

char *hostname = host name, or

IP addresses expressed as a character string

short int port = TCP/IP port number

This function establishes a connection between the computer system and the Modicon PLC

• int Disconnect ();

This function breaks a connection between the computer system and the Modicon PLC

• int read4x (int offset, int noElements, void *buf);

where:

int offset = PLC memory offset in 16 bit words from which to read data

int noElements = number of 16 bit integer data elements to read

void *buf = address of user supplied data buffer

This function reads a single data block of 16 bit integers values from the PLC user register memory starting at ‘offset’ words from 40000 and stores the results in a user defined buffer

• int writ4x (int offset, int noElements, void *buf);

where:

int offset = PLC memory offset in 16 bit words from which to write data

int noElements = number of 16 bit integer data elements to write

void *buf = address of user supplied data buffer

This function writes a single block of user supplied 16 bit data words to the PLC user register memory starting at ‘offset’ words after 40000