Moxa ioPAC 8500-2-M12-C-T [45/66] Modbus tcp master

Developer's Guide for Moxa RTU Controllers Programmer's Guide

2-37

Modbus/TCP Master

MX_Modbus_Tcp_Master_Open

INT32 MX_Modbus_Tcp_Master_Open(UINT8 ipAddress[], UINT16 tcpPort, UINT32 cTimeoutMs,

UINT32 *sHandle);

This function establishes a TCP connection to the target IP address. If the returned code is MODBUS_ERR_OK,

the connection handle sHandle should be closed by the function MX_Modbus_Tcp_Master_Close.

Input Parameters

ipAddress

The IP address of the Modbus slave

tcpPort

The TCP listened port of the Modbus master

cTimeoutMs

Modbus address

Output Parameters

sHandle

Returned connection handle.

Return Value

MODBUS_ERR_OK

MODBUS_ERR_LIB_INIT

MODBUS_ERR_PARAM

MODBUS_ERR_SOCKET: Socket error

MODBUS_ERR_TIMEOUT: Connect timeout

MODBUS_ERR_CONNECT: Connect to target error

MODBUS_ERR_HANDLE: No more handles

MX_Modbus_Tcp_Master_Close

INT32 MX_Modbus_Tcp_Master_Close(UINT32 sHandle);

This function closes the TCP connection established by MX_Modbus_Tcp_Master_Open.