I am using PM591 and ethernet module CM 597 to receive udp packets which are coming after every 1 second. 

In codesys, I've used ETH_UDP_REC block to receive udp packets. It is actually a packet of 15 bytes.

I am storing these packets in string like this:

Packet: STRING (15)

But, first time when i run code it receive udp packets then it gets stucked. It does not receive more data. Please help me to resolve this issue. 

TIA