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Introduction to Syntax and Procedures

Data Command Set

• Generic Modem Commands
• DTE Interface
• Call Control
• Modulation Control Commands
• Error Control Commands
• Data Compression Commands
• Diagnostic Commands
• V.92 +P Commands
• S Parameters

Result Codes

Glossary

Regulatory Information

Limited Warranty

Diagnostic Commands

#UD - Last Call Status Report

#UD is an action command requesting reporting of logged operation events. It does not take parameters and must be the last command in the command line.

The modem logs aspects of their operation for each call, and saves these results until cleared by one of the following events:

1. Power off
2. Hard reset (e.g., negate DTR with &D3 set; reset button)
3. Soft reset = ATZ or AT&F
4. ATD command issued
5. ATA command issued
6. Automatic answer (e.g., set register S0>0 and ring detected)

These results are NOT cleared by changing DTR, V.24 circuit 108.2, if &D0, &D1 or &D2.

Data Call State Model

For purposes of this command, there are four data call states, and associated status issues:

Call Setup
- Calling DCE: get dial tone, generate dial digits, detect call progress signals.
- Answering DCE: detect ringing, detect CallerID, etc.

Negotiation
- V.25 calling tone/answer tone exchanges
- V.8 or V.8bis call function negotiations
- V-series modem carrier detection and training
- Modem-to-modem protocols (e.g., V.42, V.42bis).

Data Transfer
- Bit-error rates, for each direction
- Rate renegotiation
- Retraining

Call Termination
- protocol disconnect signals
- carrier disconnect signals
- loss of carrier
- excessive error rates

Command Syntax

In response to this command, the modem will report one or more lines of information text as defined below. Information text format conforms to V.250; each line is preceded by a <CR><LF> pair, and terminated by <CR><LF>. (CR and LF characters may be changed by writing new values to the contents of registers S3 and S4, respectively.)

The modem may generate a single line or multiple lines, followed by a standard OK final result code. For example, if call setup failed, only that result is useful. Each information text line is formatted as follows, including one or more key=value pairs:

Syntax

#UD

Response

DIAG <token key=value [[key=value] [key=value]]...>

Defined Values

Unless otherwise noted, all values are hexadecimal numbers. Any numeric values from tables in ITU V.58 are converted to hexadecimal. Multi-digit values are reported MSD first. Leading 0's may be deleted.

Monitoring an active connection

This command is intended for use after call termination. However, codes are defined so that a modem can respond before the first call is placed, and during a call for live monitoring purposes. For example, key 60, call termination, has value 1 defined, indicating that the call is still in progress.

There are at least two ways to do this. First, the DTE could switch the modem to On-Line command state, issue the command, capture the responses and then issue an ATO command. For smoother on-line monitoring, in-band means defined in ITU V.80 are recommended if available in the modem. If V.80 methods are used, each response line shall be a separate extended in-band message.

Notes for Tables

1. The modem may insert a delay (e.g., 10 ms) between information text lines.
2. The code tables include values for data and fax calls. Some of the codes are applicable only to data calls (e.g., data compression), some are applicable only to call origination (e.g., busy, answering signal detection) and some are applicable only to the answering modem (e.g., calling signal detection).

callCleared codes from 3.6.4/V.58-1994

callCleared: indicates that the DCE has gone on-hook and that the previously existing network connection has been cleared. These value are hex, converted from decimal in V.58.

Key	Value(s)	Definition
0	2 digits	Diagnostic Command Specification revision number, digit.digit
1	Table 3-4	Call Setup Result code
2	Table 3-5	Multi-media mode
3	Table 3-6	DTE-DCE interface mode
4	String	V.8 CM octet string, same format as V.250, in quotes
5	String	V.8 JM octet string, same format as V.250, in quotes
10	0-2F	Received signal power level, in-dBm (0-43)
11	0-1F	Transmit signal poer level, in -dBm (e.g., 0-17)
12	0-64	Estimated noise level, in -dBm (e.g., 10-90)
17	0-FFF	Round Trip delay, in units of ms
18	Table 3-7	V.34 INFO bit map
20	Table 3-8	Transmit Carrier Negotiation Result
21	Table 3-8	Receive Carrier Negotiation Result
22	0-1F40	Transmit Carrier symbol rate (0-8000) in symbol/s
23	0-1F40	Receive Carrier symbol rate (0-8000) in sybol/s
24	0-FAO	Transmit Carrier frequency (0-4000) in Hz
25	0-FAO	Receive Carrier frequency (0-4000) in Hz
26	0-FAOO	Initial transmit carrier data rate (0-64000) in bit/s
27	0-FAOO	Receive transmit carrier data rate (0-64000) in bit/s
30	0-FF	Temporary carrier loss event count
31	0-FF	Carrier Rate re-negotiation even court
32	0-FF	Carrier Retrains requested
33	0-FF	Carrier Retrain requests granted
34	0-FAOO	Final transmit carrier data rate in bit/s
35	0-FAOO	Final receive carrier data rate in bit/s
40	Table 3-9	Protocol Negotiation Result
41	0-400	Error Control frame size in bytes
42	0-FF	Error control link timeouts in transmission
43	0-FF	Error control link NAKs received
44	Table 3-10	Compression Negotiation Result
50	0-2	Transmit flow control: 0 = off; 1 = DC1/DC3; 2 = V.24 circuit 106/133
51	0-2	Receive flow control: 0 = off; 1 = DC1/DC3; 2 = V.24 circuit 106/133
52	0-FFFFFFFF	Transmit characters sent from DTE
53	0-FFFFFFFF	Received characters sent to DTE
54	0-FFFF	Transmit characters lost (data overrun errors from DTE)
55	0-FFFF	Received characters lost (data overrun errors to DTE)
56	0-FFFFFFFF	Transmit I-Frame count, if error control protocol running
57	0-FFFFFFFF	Received I-Frame count, if error control protocol running
58	0-FFFF	Transmit I-Frame error count, if error control protocol running
59	0-FFFF	Received I-Frame error count, if error control protocol running
60	Table 3-11	Termination Cause
61	O-FF	Call Waiting event count

Code	Definition
0	No previous call (modem log has been cleared since any previous calls)
1	No dial tone detected
2	Reorder signal detected, network busy
3	Busy signal detected
4	No recognized signal detected (e.g., no signal, or nothing recognizable)
5	Voice detected * if this is a voice modem (e.g., V.253) operating in voice mode (e.g., +FCLASS=8.0)
7	Data Answering signal detected (e.g., V.25 ANS, V.8 ANSam)
8	Data Calling signal detected (e.g., V.25 CT, V.8 CI)
9	Fax Answering signal detected (e.g., T.30 CED, DIS)
A	Fax Calling signal detected (e.g., T.30 CNG)
B	V.8bis signal detected

Code	Definition
0	Data Only
1	Fax Only
2	Voice
9	Video-telephony, H.324
A	Other V.80 call

Code	Definition
0	Async data
1	V.80 transparent synchronous mode
2	V.80 framed synchronous mode

Bits	Source bits	Definition
31-30	INFO0 bit 20; 0
20-29	INFOc bits 79-88
16-19	INFOc bits 26-29 or 35-38 or 44-47 or 53-56- or 62-65 or 71-74	Pre-emphasis field, selected by the symbol rate chosen
12-15	INFOa bits 26-29
10-11	MP bit 50; 0
0-9	INFOa bits 40-49

gstnModulationSchemeActive from 3.7.2/V.58

Example Modem Response and Usage

Example #UD commend response are shown in