Communication issue with 550sr

I just started working with 550sr. Depending on boot up sequence I get two “modes”; on module red LED is always on, and two green leds flash quickly (one being on, one off at any time, switching in between); or where only middle led flashes more slowly.
Either way, in both of these modes module is found from the LAN side by config app.

However, I need to control module via RS232 (115200 8N1 no flowctrl, as listed as default), but module is not responding anything, despite being found in LAN (I haven’t changed the settings, just checked that module is found). I’ve tried AT\r\n and +++ sequence both, but nothing is sent by module. I’ve verified (with oscilloscope) that RX line does receive command correctly, but TX line remains constantly high with nothing happening.

What might be wrong here?


First, refer to below link.
lt link is 550sr configuration tool guide.

And, Did you checked AT command enable check box in configuration tool?
It must be checked in box.

And Did you setting 2B, 2B, 2B code?
It was ASCII code. So, setting to 2B(+) , 2B(+), 2B(+).

And AT command operation must be added to $0d$0a(\r\n) in a packet.(tail)
It is using HEX code.

Thank you

Yes, AT command check box is enabled and code is set to 2B,2B, 2B (ie, mentioned +++).

0D,0A was added to end of AT commands.

Yet module doesn’t seem to be responding anything via serial port, while ethernet side seems to be working fine. I assume that since I am able to fetch configuration data with Wiznet config tool, the module is in correct operating mode where it should accept also AT commands?


First, Did you used wiz550sr-evb?
If you not used wiz550sr-evb, You connect to wire or another boards.
WIZ550sr has 2 serial ports. (Data communication port is UART 1)

And UART2 is display debug message port.

So, you must be send “+++” mesage to UART1.

And then check the messag.(below message)


Thank you

Module is on custom board that connects to our MCU board. I am using J2 pins 1 (for sending data to wiz550) and 2 (reading data from wiz550) (so, UART1) to connect the module to serial port of our main board MCU. Flow control (pins 3,4) is not currently used, as indicated by config tool.

I have sent “+++” message to UART1 (pin 1). I have verified with oscilloscope with serial decode that data sent to module is valid and has correct parameters. After this there I see absolutely no activity of any kind on pin 2, it remains high all the time.

I suspect that there is some issue with initialization/startup sequence (ie, timing how power, /reset and /hwtrig lines should be controlled during startup?). Now the board is working as expected although nothing was changed between previous attempts and now except power cycling entire project overnight.

Also, is there any explanation about three board leds (red + 2 green), what do they exactly signify?