Internet PLC Forum

General => Technical support => Topic started by: JodyOno on May 13, 2013, 01:53:53 PM

Title: Host Link Protocol Response
Post by: JodyOno on May 13, 2013, 01:53:53 PM

I have a Windows application that successfully communicates with an FMD88-10 using the Host Link Protocol.  I have noticed that when there is excessive traffic on the Internet connection to the PLC, the FMD88 will respond with HO* instead of whatever the proper response may be for the command that I have just sent.  I cannot find any reference to such a string in the user manual for the FMD88-10.  Is HO* some kind of error response?

Title: Re:Host Link Protocol Response
Post by: support on May 14, 2013, 06:42:17 PM

HO* is not a valid response from the PLC and doesn't sounds like it is a response from the PLC.

Depending on how your applicaition is written, you may have lost some characters when reading from the Ethernet buffer.

You can use wire-shark program to sniff the TCP/IP communication between the application program and the PLC and see what transpires between the two.

Even though point-to-point protocol will work, it may be better to use the multi-point protocol which includes checksum (FCS) and allow you to verify if the received string contain errors.