# TCPServer

You can use the TCPServer function to define a spreadsheet cell as a TCP/IP server, which listens to connections in for another TCP/IP device to connect and share data over the network.

Note:

- TCPServer generates an event after receiving a packet. This event updates the spreadsheet.

- TCPServer accepts only one established connection. If a new connection request comes while there is already a connection, the old connection closes and the new connection replaces it.

## TCPServer Inputs

Parameter | Description
--- | ---
Port Number | Specifies the port number at which the TCPServer receives connections from TCP/IP devices. The port number is an unsigned 16 bit port number. 0 is not a valid port. The default port number is 3000. Note: You need to assign the port number entered here on the server.
Packet Type | Defines the formatting of the data string communicated between TCP/IP devices.
Type | Description
--- | ---
0 = String CR+LF (default) | ASCII format. When a TCP Spreadsheet function is sending, the software appends ASCII characters 13 (Carriage Return) and 10 (Line Feed) to the data string; when receiving, CR+LF terminates the data string.
1 = String CR (13) | ASCII format. When a TCP Spreadsheet function is sending, the software appends the ASCII character 13 (Carriage Return) to the data string; when receiving, CR terminates the data string.
2 = String LF (10) | ASCII format. When a TCP Spreadsheet function is sending, the software appends the ASCII character 10 (Line Feed) to the data string; when receiving, LF terminates the data string.
3 = String Nullchar (0) | ASCII format. When a TCP Spreadsheet function is sending, the software appends the ASCII character 0 (Nullchar) to the data string; when receiving, Nullchar terminates the data string. Note: Regardless of the Packet Type, when an In-Sight vision system receives data, the ASCII character 0 (Nullchar) terminates the data string.
5 = String with Custom Terminator | ASCII format. When a TCP Spreadsheet function is sending, the software appends the specified Terminator to the data string; when receiving, the specified Terminator terminates the data string.
Terminator | Specifies the byte value you use when you specify String with Customer Terminator or Binary with Customer Terminator for the Packet Type.
Max Packet Size | Specifies the maximum packet size that TCPServer can receive. If the remote sender exceeds the maximum packet size, ReadDevice shows an #ERR.

## TCPServer Outputs

Returns | A Device data structure. Returns #ERR if any of the input parameters are invalid.
Results | When you insert the TCPServer function into a cell, a WriteDevice function is automatically inserted in the adjacent cell to the right.