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3.2.8 Synchronous Access Mode Commands
3.2.8.1 +ESA - Configure Synchronous Access Mode
This extended-format compound parameter controls the manner of operation of the
Synchronous Access Mode in the modem.
Enabling Synchronous Access Mode enables the use of the 8-bit command characters
defined in Table 9/V.80 of the Draft ITU-T Recommendation V.80 (DATA
COMMUNICATION OVER THE TELEPHONE NETWORK; In-Band modem Control and
Synchronous Data Modes for Asynchronous DTE).
Syntax
+ESA=[<trans_idle>[,<framed_idle>[,<framed_un_ov>[,<hd_auto>[,<crc_type>[,<nrzi_e
n>[,<syn1>[,<syn2>]]]]]]]]
Defined Values
<trans_idle> Decimal number which specifies the bit sequence transmitted by the
modem when a transmit data buffer underrun condition occurs, while operating in
Transparent sub-Mode. The options are:
0 In Transparent sub-Mode, modem transmits 8-bit SYN sequence on idle. Modem
receiver does not hunt for synchronization sequence (default and fixed).
<framed_idle> Decimal number which specifies the bit sequence transmitted by the
modem when a transmit data buffer underrun condition occurs immediately after a flag,
while operating in Framed sub-Mode.
The options are:
0 In Framed sub-Mode, modem transmits HDLC flags on idle (default and fixed).
<framed_un_ov> Decimal number which specifies the actions undertaken by the modem
when a transmit data buffer underrun or overrun condition occurs immediately after a
non-flag octet, while operating in Framed sub-Mode.
0 In Framed sub-Mode, modem transmits abort on underrun in middle of frame.
(Default.)
1 In Framed sub-Mode, modem transmits a flag on underrun in middle of frame,
and notifies DTE of underrun or overrun.
<hd_auto> Decimal number which specifies whether or not, in V.34 half-duplex
operation, additional
procedures besides those specified in § 12/V.34 will be performed by the modem when
switching
from primary channel to secondary channel operation, and vice versa. This
subparameter should
not be commanded.
<crc_type> Decimal number which specifies the CRC polynomial used while operating in
Framed sub-Mode.
The options are:
0 CRC generation and checking disabled. (Default.)
1 In Framed sub-Mode, use the 16-bit CRC specified in V.42.
2 In Framed sub-Mode, use the 32-bit CRC specified in V.42.
<nrzi_en> Decimal number which specifies if Non Return to Zero Inverted (NRZI)
encoding is to be used by the modem for transmit and receive data. The options are:
0 NZRI encoding and decoding disabled (default and fixed).
<syn1>, <syn2> Decimal number which specifies the octet value(s) to be used while
performing character-oriented framing. <syn1> is to be commanded to 255 (FFh);
<syn2> is not to be commanded.
Reporting Current or Selected Values
Command: +ESA?
Response: +ESA:
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