Advantech PCM-3601 user manual Flow Control, Non-Volatile Memory Nvram

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supports MNP5, the connection can only be established in MNP5 mode.

You should use the V.42bis recommendations as long as the on- line modem at the remote end supports the same. This way, you can achieve higher data throughput. To select the ECDC mode, use the command \N.

2.8Flow Control

While on-line, your modem is between your computer and the remote modem (or the remote computer, if you consider the remote modem as a transparent device). Your modem communicates with your computer (the local computer) through RS-232 serial port interface, and communicates with the remote modem via telephone line.

If data comes to your modem faster than it goes out, some data may be lost because your modem can not pass on all the received data to the other end. To overcome this problem, your modem is equipped with a data buffer to store excess data received. Once the buffer is full, your modem must signal the sending device to stop transmission. When the buffer is clear, your modem signals to resume data transmission. This is called flow control.

Two kinds of flow control methods are commonly used, the hardware flow control and the software flow control. Hardware flow control is also called RTS/CTS control, as it uses the RS-232 hardware signals (RTS and CTS) to stop or resume data transmission. This is the best method of flow control because you can send any data characters using this method.

The software flow control uses two data characters (XON and XOFF) to indicate when the sending device shall stop or resume. Since it uses data characters as control, you can not send binary data or file-transfer protocols such as XMODEM with this type of flow control. To select a method for flow control, use command \Q. You should use hardware flow control at all times, if your modem supports it.

2.9Non-Volatile Memory (NVRAM)

The NVRAM is a special type of read-write memory element which can retain data even when the power is turned off. Your modem NVRAM retains configuration profiles and telephone numbers.

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Contents PCM-3601 Copyright notice Data modem throughput up to 115.2K bps Unpacking and InstallationFeature Fdsp Full -duplex speakerphone ChapterPackage Error Correction & Data CompressionVoice/audio mode Nvram directory and stored profilesLook at the Modem Card Unpacking the ModemPC/104 FaxModem Card Setting the COM Port and Interrupt of the Modem Card Installing 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 Fundamentals Modem BasicsData 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 ControlActive Configuration Area ACA Factory Default Profile FDPStored Configuration Profile SCP Major Stored Configuration Profile Major SCPStored Telephone Numbers STN Command State and Data State Modem Operation and Response CodesEscape Sequence +++ Issuing Commands Command BufferDeleting Commands Modem AT Response Codes Operation Commands AT CommandsPrefix, Repeat and Escape Commands Dial Commands and Dial ModifiersW1 Enable V.42 response codes, display DCE speed M0 Set modem for async operation P0 M/B ratio 39/61USA Call Back Security Command Set Option Lease Line/Dial Line 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 CommandAutomatic Retrain Ecdc Operation Mode SelectionMNP Response Code Option Data CompressionAppendix a Modem RegisterRegister Summary 1711h XON Character S33 255 Result Codes Appendix B+FCERROR Short Form Long Form Fax Command Codes Fax Class Fax Class II CommandsAppendix C +FDIS Appendix D Installation of Modem Driver in Win 95/98
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