Manual 7XV5655-0BB00
SIEMENS AG
Page 45 of 79
C53000-G1176-C175-3
TC57 Settings (Ethernet)
If a frame in TC57 format is received via the RS232 interface, it is sent immediately via
the Ethernet without a "timeout". This procedure clearly increases the performance of
the connection and ensures uninterrupted transmission of frames.
The IEC 60870–5–1 and IEC 60870–
5–2 standard defines four standard
frame formats for the data link layer.
They are:
TC57 Format FT 1.1
TC57 Format FT 1.2
TC57 Format FT 2
TC57 Format FT 3
Frame formats FT 1.2, FT 2 and FT 3
have a frame of fixed length.
The frame with variable length for FT 2
and FT 3 has a header of fixed length.
This contains "Start character",
"Length", "User data" and "Checksum".
The user must select the required format and enter the values for "Fixed frame length"
and "User data length".
The value in the "Fixed frame length" edit box is in the range 2 to 255 bytes.
The value in the "User data length" edit box is in the range 2 to 14 bytes. The value only
refers to "User data" from the header.
Note
: For the protocols IEC60870-5-103, VDEW or for the protocol used by DIGSI®,
the format FT 1.2 (Header length = 0 byte and Fixed Frame length = 2 byte) is required.