Hi guys,

I’ve got a TCP Stream to the Hologram cloud socket working and can successfully send messages to it using the Hologram Dashboard Messaging tab. The connection was established using AT+CIPOPEN=0,\"TCP\",\"%s\",%u,8000\r, where %s is the IP and %u is the port.

When I receive a message, I try to immediately reply to it using AT+CIPSEND=0,%u\r, where %u is the length of my outgoing string. I then wait 20ms and then send the string of data. Reading the buffer, I get the error +CIPERROR: 4. Checking the SIMCOM manual, it seems that this error represents Operation not supported. Am I doing something wrong? Can I truly not send outbound TCP, because if so I’m going to be requesting a refund. Thanks!

It’s definitely supported by our SIMs. Maybe the socket has closed already or isn’t available for writing. I’m not very familiar with the SIMCOM hardware but you should see if they have any examples of doing that with AT commands and try to run through the steps manually by pasting into a terminal to see if you’re doing everything correctly.

Looking at this closer in the docs and have a couple other questions. Are you reading the data from the socket before trying to send?
Are you setting up the socket as a listening socket? I feel like for a listening socket you usually leave the server IP and port blank or set to something like That CIPOPEN command doesn’t seem correct.

So I read the socket TCP data and then try to send a reply. Should I be using AT+SERVERSTART instead of AT+CIPOPEN?

Ah yep, that’s the one

This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.