Silicon Laboratories SI2494/39 manual Epos Electronic Point of Sale Applications, 15. V.80 Mode

AN93

5.13. EPOS (Electronic Point of Sale) Applications

EPOS applications are discussed in "Appendix A—EPOS Applications" on page 257.

5.13.1. EPOS Fast Connect

The ISOmodem supports several fast connect modes of operation to reduce the time of a connect sequence in originate mode.

5.13.2. EPOS V.29 Fast Connect

In addition to the low modulation speed fast-connect modes, the modem (only Si2493/57/34/15) also supports a fast-connect mode based on the 9600 bps V.29 fax modulation standard. V.29 Fast Connect is available as a patch. Please contact Silicon Laboratories for additional details.

5.14. Legacy Synchronous DCE Mode/V.80 Synchronous Access Mode

The ISOmodem supports two different DTE interfaces to implement an Asynchronous DTE to Synchronous DCE conversion. Table 84 provides high-level options to choose between the Legacy Synchronous DCE Mode and the newer V.80 synchronous access mode.

Table 84. Synchronous Mode Overview

Mode	U Register	AT+ES
		Settings
Neither	U7A [2] = 0	+ES = D,,D
Legacy Synchronous	U7A [2] = 1	+ES = D,,D
DCE Mode
Synchronous Access		+ES = 6,,8
Mode

The synchronous access mode has more features than the Legacy Synchronous DCE Mode. For new designs, use of the newer synchronous access mode interface is recommended. Otherwise, existing software written with the Legacy Synchronous DCE Mode interface can still be used as long as the AT+ES command settings are not changed from the default value.

5.15. V.80 Mode

As shown in Table 85, the synchronous access mode is chosen by using the AT+ES=6,,8 command setting.

When using the synchronous access mode, it is expected that the AT\N0 command will be used to disable all other error correction protocols that may interfere with V.80 synchronous access mode operation.

The V.80 Mode has two distinct submodes. Switching between these two submodes can be accomplished within the confines of the same connection through the use of In-Band commands. The submodes are:

Transparent Submode

Framed Submode

The Transparent Submode creates a direct bit-by-bit translation from the DTE to and from the DCE. Any application that requires a method of reconstructing a serial bit-stream at the DCE can use the Transparent Sub- mode.

The Framed Sub-mode represents data at the DCE in HDLC/SDLC frames. This submode is typically used in point-of-sale terminals. A common feature used in conjunction with the Framed Submode is the use of the 16-bit CRC. When used with the CRC option, the Framed Submode can be used in the same applications currently using the Legacy Synchronous DCE Mode.

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