Pixsys CNV510-PBUS-RTU-A, User Manual

Page: 21 / 32

pag. 21
ASYNC MODBUS REQUEST:
With the Async Modbus Request is possible to send an Asynchronous Modbus Request form the PROFIBUS to the Modbus network.
To use this feature there are 8 bytes in write where the master PROFIBUS can send the parameters of the request and 4 bytes in read where the result of the Modbus
communication is saved.
The parameter in write are:
BYTE NAME DESCRIPTION
1 Control_TX It is the Control byte used to send the request
2 Spare Not used/ Reserved
3 ID_Device The ID of the Modbus Slave where to send the request
4 Function_Code The Function Code of the request
5, 6 Address Address of the Status/Register to read/write
7, 8 W_Value Value to write (only if it is a Write request)
The Status in Read are:
BYTE NAME DESCRIPTION
1 Control_RX It is the Control Byte used to send the status of the request modbus
2 Status_Request It is the result of the Modbus request
3, 4 R_Value Read value (only if it is a Read request)
The permits values for the “Function Code” are:
•
1  Read one Coil Status
•
2  Read one Input Status
•
3  Read one Holding Register
•
4  Read one Input Register
•
5  Write one Coil Status
•
6  Write one Holding Register
•
15  Write one Coil Status
•
16  Write one Holding Register