If register should be written or read.
This value is passed to the calback functions which support either reading or writing register values. Writing means that the application registers should be updated and reading means that the modbus protocol stack needs to know the current register values.
See also: eMBRegHoldingCB(), eMBRegCoilsCB(), eMBRegDiscreteCB() and eMBReglnputCB().
Enumeration values: MB_REG_READ Read register values and pass to protocol stack.
MB_REG_WRITE Update register values.
Note: Note all ports implement this function.A port which wants to get an callback must define the macro MB_PORT_HAS_CLOSE to 1.
Returns: If the resources where released it return eMBErrorCode:: MB_ENOERR. If the protocol stack is not in the disabled state it returns eMBErrorCode:: MB_EILLSTATE.
Examples: LINUX/demo.c, MCF5235TCP/demo.c, STR71XTCP/demo.c, WIN32/demo. cpp, and WIN32TCP/
demo. cpp.
his function disables processing of Modbus frames.
Returns: If the protocol stack has been disabled
