GE F650 Instruction Manual page 737

D.2 TECHNICAL DESCRIPTION APPENDIX D
D.2TECHNICAL DESCRIPTION
ASDU is the information unit used for data transmission. An ASDU may have data inside or not. The ASDU is encapsulated
in another package of the link layer. ASDU address takes up 2 bytes.
Communication frames can be control or data frames. Control strings do not have ASDU inside.
A frame is consist on 3 parts. (2 of them are not always present):
Link data + [ASDU header+ [ASDU data]]
The data between brackets can be omitted
In IEC104 communication is made by TCP/IP protocols. Actually, it is a TCP communication. The default port is the 2404.
The F650 is listening as a server. Only one client is attended at time.
D
D-2 F650 Digital Bay Controller GEK-106310AB