3Com 56K Testing the Business Modem using S-Resister, Remote digital loopback using keyboard data

Testing the Business Modem using S-Resister 16 14-9

Testing the Business Modem using S-Resister 16

Register S16 is a bit-mapped register (See Appendix A, S-Registers, for instructions for setting bit-mapped registers).

For your modem to use	Use one of these command
Remote digital loopback with built-in test pattern	ATS16=4 or ATS16.2=1
Remote digital loopback using keyboard data	ATS16=8 or ATS16.3=1

Earlier modems require bit 3 to be enabled to grant digital loopback testing to a remote device. The Business Modem requires the &T4 setting instead. To perform remote digital loopback testing with a modem that does not use the &T test command, that modem should be set to S16=8.

Analog Loopback (AL) To use the modem's Test Pattern (S16, bit 2) instead of typing your own S16=1D data, see RDL Testing Using a Built-in Test Pattern (S16=4).

1Send AT&M0&N3S14.0=0 to the modem to prepare for testing.

This command disables error control, fixes the connection rate at 2400 bps, and makes the Business Modem return to command mode when you type +++.

2Send ATS16=1D. The modem enters AL mode and sends a CONNECT result code. The MR status light flashes.

3Type data to the modem for it to transmit, loop to its receiver, and output to the screen.

An alternative is to use the Test Pattern, described later.

4Send the escape code, +++, and then ATH to end the test.

5Send AT&M4, unless you used a reset command (ATZ or ATZ!).