How Do I Receive Frames Without CRLF with the LabVIEW TCP Read Function?

Updated Dec 10, 2019

Reported In

Software

  • LabVIEW

Issue Details

My PLC uses DLE+STX to start frames and DLE+ETX to end frames. There is no CRLF. When I try to read data through the TCP Read function in LabVIEW, a timeout occurs. What should I do?

Solution

The TCP Read function supports four modes: Standard, Buffered, CRLF, and Immediate. In general, the TCP Read function separates frames based on CRLF. If there is no CRLF in the frame, you can use Immediate mode. Immediate mode can be used to receive frames without CRLF. This mode receives data in bytes to read regardless of the frame format. When using this mode it can be helpful to know the exact length of the entire frame.