SI2457-D-FS Silicon Laboratories Inc, SI2457-D-FS Datasheet - Page 166

• Manufacturer Part Number: SI2457-D-FS
• Description: IC ISOMODEM SYSTEM-SIDE 16SOIC
• Manufacturer: Silicon Laboratories Inc

Specifications of SI2457-D-FS

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

AN93
166
0D 0A 43 4F 4E 4E 45 43 54 20 31 32 30 30
0D 0A
19 BE 20 20
19 B0
19 B2
19 B1
19 B0
19 B2
30 93
19 B1
19 B2
30 93
19 B1
Data
Table 104. Bit Errors
Beginning of Packet
Beginning of Packet
Beginning of Packet
Beginning of Packet
Beginning of Packet
Rev. 1.3
Is an indication the modem has detected a pattern with
more than 6 marks in a row. Once this occurs, the
receiver begins looking for HDLC flags. Until the occur-
rence of HDLC flags, 19 B2 and subsequent data are
discarded.
This pattern has three meanings.



The data can be analyzed as follows with valid data
shown in bold.
Received first flag.
A spurious byte received with more than 6 mark bits in a
row. The modem is looking for HDLC flags.
HDLC flag detected.
Good Packet.
If a 1-bit error is received in an HDLC flag, the modem
assumes a new single-byte packet. Since a 1-byte
packet is invalid, 19 B2 is generated by modem.
Good Packet
If the receiver is looking for HDLC flags, 19B2 means
that the receiver has found an HDLC flag.
If 19B2 is received after a packet has started (prior
data exists), the receiver assumes the CRC check
does not match the FCS bytes sent by the remote
transmitter and declares the packet bad.
An isolated 19 B2 pattern (no preceding data) is
normal. This can occur when the following example
data pattern is seen: 7E 7E XX 7E 7E (where XX can
be up to 2 bytes of non-FLAG bit patterns at the
DCE).
CONNECT 1200
tx 1200 rx 1200
Meaning