Advantech PCM-3601 user manual On-Line Speed DCE Speed, Serial Port Speed DTE Speed

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communicate with both the remote modem and local computer, through the telephone line and serial port cable, respectively. Figure 1-1 describes the DCE speed relationship between modems.

The speed over the telephone line at which your modem communicates with the remote modem is called the on-line speed. Since the modem is Data Communications Equipment, the communications speed is called the DCE speed.

On the other hand, the speed over the serial port at which your modem communicates with the local computer is called the serial port speed. Since the computer is Data Terminal Equipment, it is called the DTE speed.

2.5On-Line Speed (DCE Speed)

Your modem supports one or more communication protocols, depending on its modem type. When your modem answers a call and establishes a connection, it adjusts its speed according to that of the calling modem. As a result, the speed at which the calling modem dials becomes the on-line speed.

2.6Serial Port Speed (DTE Speed)

Each time the modem receives a command string from the computer, the AT prefix instructs the modem of the serial port speed. This speed remains as the active serial port speed, (i.e., the active speed DTE speed).

For example, if your modem is set at 2400bps and the remote modem is calling at 1200bps, the connection is established at 1200bps. Your modem sends the response code CONNECT 1200” at 2400bps to the local computer and then adjusts its DTE speed to 1200bps. Your modem will no longer recognize characters received from the local computer at 2400bps. If you are writing communications software, be sure to have the local computer determine the speed from the response code and adjust its serial port speed accordingly.

In normal applications, the baud rate adjustment capability of your modem should be enabled so that the DTE speed shall always follow the DCE speed. you can issue the \J command to turn the serial port adjustment on or off.

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Contents PCM-3601 Copyright notice Feature Fdsp Full -duplex speakerphone Unpacking and InstallationChapter Data modem throughput up to 115.2K bpsVoice/audio mode Error Correction & Data CompressionNvram directory and stored profiles PackageLook at the Modem Card Unpacking the ModemPC/104 FaxModem Card Installing the Modem Card Setting the COM Port and Interrupt of the Modem CardSerial Port and Interrupt of the Modem Card Communications Software Configuration Testing the Telephone Line Prior to ConnectionSoftware Configuration Tips Getting Started AT&P0DPModem Basics Modem FundamentalsData Format Speeds of the Modem Communications ProtocolSerial Port Speed DTE Speed On-Line Speed DCE SpeedError-Correction and Data Compression Ecdc Non-Volatile Memory Nvram Flow ControlStored Configuration Profile SCP Factory Default Profile FDPMajor Stored Configuration Profile Major SCP Active Configuration Area ACAStored Telephone Numbers STN Modem Operation and Response Codes Command State and Data StateEscape Sequence +++ Command Buffer Issuing CommandsDeleting Commands Modem AT Response Codes Prefix, Repeat and Escape Commands AT CommandsDial Commands and Dial Modifiers Operation CommandsW1 Enable V.42 response codes, display DCE speed M0 Set modem for async operation P0 M/B ratio 39/61USA Lease Line/Dial Line command set Option Call Back Security Command Set OptionLease Line Backup Dial Line command set Option Auto Dial/Redial mode Option Display Dialing Number if AT&In Command supportOptionSet Break Control 42bis and MNP CommandMNP Response Code Option Ecdc Operation Mode SelectionData Compression Automatic RetrainModem Register Appendix aRegister Summary 1711h XON Character S33 255 Result Codes Appendix B+FCERROR Short Form Long Form Fax Class II Commands Fax Command Codes Fax ClassAppendix C +FDIS Appendix D Installation of Modem Driver in Win 95/98
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