Manual 7XV5655-0BB00
C53000-G1176-C175-3
Page 48 of 79
SIEMENS AG
Protocol Code TC57 for Transmission into the Ethernet
This procedure considerably enhances transmission rates when TC57
compatible protocols are transmitted. If the RS232 interface detects a protocol
package of this type, it is transmitted as a block via the Ethernet immediately,
without waiting for a timeout to elapse.
The Serial Modem can be adapted to various standards.
The IEC 60870–5–1 and IEC 60870–5–2 standards define four standard frame
formats for the data link layer:
0 = Format FT 1.1
2 = Format FT 2
1 = Format FT 1.2
3 = 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 "Header length".
Protocol code for IEC 60870-5, VDEW and DIGSI®
The IEC 60870–5–102 / 103, VDEW, DIGSI® V3 and DIGSI® 4
protocols are identical to or similar to this specification so that the protocol code
of this Serial Modem can be used.
This is done by activating the protocol code, selecting format FT1.2 and setting
a fixed frame length of 2 bytes.
