SE100 delivered data packet is being cut or cut data is delayed till next received data packet

Please set Packet Mode of Serial Input as Enabled as below screenshot.

When Serial Input Packet Mode is set as enabled, each data packet sent to SE-100 serial port will be hold for 10ms waiting if more data coming in. If there is no more data coming in within 10ms, Then the whole received data packet will be sent to Ethernet port of SE-100, so that data packet will not be cutted.