WAN IA not sending serial request after reboot

Hi, I’m new member here, looking for help.

I have a DigiConnect WAN IA, serial port connected a Modbus Master PLC1. Serial profile configured as Industrial Automation. My destination is a PLC2 (Modbus/TCP server) which at remote site connected to internet through ADSL modem. The simplified configuration is like below:

PLC1(MB master)->WAN IA->GPRS->internet->ADSL->PLC2(MB/TCP Server)

I have managed to write data from PLC1 to PLC2 every one minute. Working fine and stable.

BUT there is one problem, if the WAN IA for some reason reboot and PLC1 still sending data to it’s serial port before GPRS is connected, then after GPRS connected (or LINK LED is on), WAN IA will only send the first serial request, the subsequence serial request will not be sent.

I have tested many times. As long as my PLC1 not sending data to WAN IA serial port before GPRS connected, it will works fine and perfectly.

Do I miss something in WAN IA’s configuration or something has been wrongly set? Please help.

I’m really very disappointed with digi’s technical support. I had posted my request to digi’s Online Support Request for 3 days, but no reply at all!!

Can sombody please help?

I see that you have a couple cases we’ve been working with you recently, so all should be in order.