Capture Settings are set-up separately for each capture channels. Once these settings have been specified, OK or Apply should be clicked. This tab specifies Echo UDP (Syslog), TCP Server and TCP Client settings.
Echo to Network Overview
ComCap can echo any captured data to the network, using UDP (syslog), TCP Server or TCP Client protocols, which are detailed in the Networking Tutorial. Effectively, this allows ComCap to convert serial data to network protocols, to be captured on remote PCs for viewing or redundancy.
Using TCP Server, data may be echoed to a maximum of five remote PCs (using TCP Client) that connect to the Local IP Address and Port. Connections are refused for connections in excess of five. TCP Client and UDP need a remote IP address to be specified, and are thus limited to a single remote PC.
TCP/IP Client may also be used for 'IP Printing' using port 9100. Many network printing will accept print data on TCP/IP port 9100.
Add Syslog Headers, Priority (Facility/Severity) Text
Specifies that syslog headers should be added to echoed lines:
Priority Only |
<14> is a Priority value where the first 7 bits of the number are a facility code and the last 3 bits are severity, selected from the drop down Facility Priority and Severity Priority lists. The Actual Priority text that will be added is show, |
Priority, Time and Host |
Also add the time and host and program name, similar in format to: <14>Mar 25 17:03:04 PC09 ComCap |
Note that Syslog headers are normally only used with UDP.
Add CRLF End of Line (UDP only)
This tick box specifies whether echoed UDP lines should have CRLF added to the end of each captured line. The TCP protocols always have CRLF added for end of line.
Echo to Remote - Remote IP Address and Port, Retry Attempts, Wait Seconds
For UDP and TCP Client, these fields allow the Remote IP Address and Remote IP Port to be specified, to which captured data will be echoed. They may not left blank or zeros. For UDP Syslog, the port is usually 514, for TCP Client it should be above 1,024, the same as that of the remote TCP Server which is listening.
UDP is an unreliable protocol where data is sent blind with no confirmation it has been received by the remote computer, which might not even exist.
TCP Client is reliable, and also needs Retry Attempts and Wait Seconds to be specified, so that connection attempts are repeated if they fail. Setting Retry Attempts to zero causes indefinite attempts to be performed.
Echo to Remote - Local IP Address and Port
For TCP Server, this is the Local IP Address for server, selected from a drop down box, usually 0.0.0.0 and the IP Port on which the server will listen for remote TCP clients, usually higher than 1,024. For UDP and TCP Client, the IP address should usually be 0.0.0.0 and the port set to zero so that Windows selects port randomly. A fixed port may be used to identify multiple UDP or TCP sessions from the same PC, but when a connection is lost there may be delay of several minutes before the port can be re-used.
Network Performance Overview
Added a new setting to improve performance when capturing high speed TCP and UDP traffic. TCP/UDP uses memory buffers to temporarily save received or sent data before ComCap is able to process it, which default to 8 Kbytes. With TCP, if data is not extracted from the buffer, the speed at which data is received will slow down, but with UDP received data is simply lost since there are no handshaking packets to confirm data needs to be delayed or resent. It should only be necessary to increase the capture buffer size if a lot of data is being received each second, maybe 16K/sec or more, or if the PC is very slow or has other CPU intensive applications so that ComCap can not get the CPU it needs. Note these new settings only appear for channels actually listening or sending data, not filter or merge channels.
Capture TCP/UDP Buffer Size (KB)
Allows the size of the TCP/UDP buffer uses to capture data to be increased from the default of 8 which means 8KB (8,192 bytes). Typically 32 or 64 should be sufficient for the large buffer. This field only appears for listening channels, not those filtered or merged from other channels.
Echo TCP/UDP Buffer Size (KB)
Allows the size of the TCP/UDP buffer uses to echo data to be increased from the default of 8 which means 8KB (8,192 bytes). Typically 32 or 64 should be sufficient for the large buffer. This field only appears if Echo has been specified for this channel.