FloBoss™ S600+ Flow Computer Modbus Specification Manual 
D301904X012 
June 2024  
  1 
Section 1.  Introduction  
This document describes the Modbus communications protocol on the FloBoss™ S600+ 
flow computer. The flow computer has 20 user-definable communication tasks. Each of 
the links may be individually configured. 
Section 2.  Physical Transport of Data 
2.1  TCP Socket 
The TCP/IP stream socket supports both master and slave links.  
If the unit is the slave on the link, it creates a server socket and listens for clients to 
connect. The TCP/IP address of the slave link is the TCP/IP address of the flow computer.  
If the unit is the master on the link, it acts as a client and attempts to connect to a remote 
server machine. When you configure the data link, you specify the TCP/IP address of the 
slave with which the master must communicate. 
The FloBoss S600+ supports communication between networks using a gateway. 
Other communication parameters are independent of the mode of data transfer. ASCII 
and RTU are supported over stream sockets and the Modbus maps are independent of 
the transport mechanism. 
2.2  Modbus TCP 
This protocol is based on the Modbus/TCP specification. The connection mechanism is 
TCP/IP which secures data transfer between any machines connected on a network. The 
Modbus protocol is encapsulated into the TCP/IP frame. 
The data transfer within the Modbus part of the protocol is standard Gould/Modicon 
Modbus. The only significant difference is that the Modbus CRC is not used: the CRC with 
the TCP/IP protocol is used instead. 
Important 
Ports 6000, 6001, 6002, 6010, 6011, and 6012 are reserved for clients using the FloBoss 
S600+ specific Modbus function code 65 and should not be used
.