The expanded version of the Win32 Slave Dll supports not only direct serial connections, but may also serve as a modbus network server using the MBAP, (Modbus API for network communications), protocol. Only one API call has been added from the basic modbus slave command set.
OpenConnection (......)
OpenTCPConnection (......)
For direct connections, defines the com port, baud rate, protocol, etc.
Returns a Handle to the connection. The dll may support multiple
serial connections as well as a network connection to the same or
different applications.
DefineDataBlock (.......)
Defines the Node Address, Point Type, Modbus Address and pointer to
a Data Array, (i.e. 100 Holding Registers Starting at Address 2000 for
Node 1). This API is used to pass the address of an array to the dll.
Your application would then fill the array with whatever data you wished,
and it would be immediately accessible to a modbus Master polling
according to the above parameters. Data points may also be written by
the Master.
EnableWriteNotification (......)
This API allows the controlling application to receive a WMsg notification
if a data point is written by the modbus master device.
SlaveStatus (.....)
Allows the app to interogate status counters, (i.e. number of
polls from master etc.)
CloseConnection (......)
RemoveDataBlock (......)
Cleans up memory allocated within the dll.
Last Updated: December 29, 1997
Backup to MODBUS Driver Page.