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Manual 7XV5655-0BB00
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
packet 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
1 = Format FT 1.2
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" (see registers S38 - 41).
Protocol code for IEC 60870-5, VDEW and DIGSI®
The IEC 60870–5–102 / 103, VDEW, DIGSI® V3 and DIGSI
protocols are identical to or so similar to this specification 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 (see registers S38 - 40).
Note: If a partner modem is dialled in an application (e.g. DIGSI®) from an
"Ethernet office modem" with the supplied modem driver, the office modem is
first reset to the factory settings with the "AT&F" command.
That also affects the TC57 settings, i.e. the settings must be passed on again
in the dialling string.
For a typical application with VDEW or DIGSI® protocol, that would be S38=1;
registers S39 and S40 are already set accordingly.
Note: All up-to-date documents, drivers and updates for our products are available
under www.siemens.com/siprotec
C53000-G1176-C175-3
2 = Format FT 2
3 = Format FT 3
Page 66 of 79
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SIEMENS AG
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