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536EX Chipset Developer’s Manual 63
Intel Confidential
Error Correction and Data Compression
+ES=m see ‘m’
Error Control Selection: The +ES=m command controls the operation of the V.42 error detection and
correction protocol in the DCE. Once a connection has been established between the DCE and DTE, the
<orig_rqst> subparameter can put the interface into synchronous access mode. In the default settings,
synchronous access mode is disabled. To change modes, send another +ES command.
m = <orig_rqst>, <orig_fbk>, <ans_fbk>
Defaults: m = 3, 0, 2
<orig_rqst> Specifies the initial requested mode of operation when the DCE is the originator. If
<orig_rqst>=6, the modem ignores the <orig_fbk> setting.
Range: 1–4, 6
0 Reserved.
1 Initiate call with buffered mode only.
2 Initiate V.42 without detection phase. If V.80 mode is in use, this is a request to disable V.42
detection phase.
3* Initiate V.42 with detection phase.
4 Initiate alternate protocol.
6 Initiate synchronous access mode when connection is completed and when in data state.
<orig_fbk> Specifies the acceptable fallback mode of operation when the DCE is the originator. This
setting is ignored if <orig_rqst>=6.
Range: 0–2, 4
0* Error control optional (either LAPM or alternative acceptable). If error control is not
established, maintain the DTE-DCE data rate and use the V.14 buffered mode with flow
control during non-error control operation.
1 Error control optional (either LAPM or alternative acceptable). If error control is not
established, change the DTE-DCE data rate to match the line rate and use direct mode.
2 Error control required (either LAPM or alternative acceptable). If error control is not
established, disconnect.
3 Reserved.
4 Error control required (only alternative protocol acceptable). If error control is not established,
disconnect.
<ans_fbk> Specifies the acceptable fallback mode of operation when the DCE is the answerer.
Range: 1, 2, 4–6, 8
0 Direct mode.
1 Error control disabled, use buffered mode.
2* Error control optional (either LAPM or alternative acceptable). If error control is not
established, maintain the DTE-DCE data rate and use local buffering and flow control during
non-error control operation.
3 Reserved.
4 Error control is required (either LAPM or alternative is acceptable). If error control is not
established, disconnect.
5 Error control required (only LAPM acceptable). If error control is not established, disconnect.
6 Error control required (only the alternative protocol is acceptable). If error control is not
established, disconnect.
8 Initiate synchronous access mode when the connection is complete and data state is entered.
Table 21. V.44/V.42/V.42 bis and MNP Data Modem Command Descriptions (Continued)
Command Default Description
NOTE: An asterisk (*) denotes the factory-default setting.
+ES=1,0,1 Buffered mode
+ES=4,4,6 MNP reliable mode
+ES=3,0,2* V.42 autoreliable mode
+ES=3,2,4 V.42 reliable mode
+ES=2,3,5 LAPM reliable mode
+ES=6, ,8 Synchronous access mode