Multi-Tech Systems MT3334HD8 manual E3 Flow Control Disable, E4 Hardware Flow Control

3 AT Commands

$EB0 enables a 10-bit format It automatically detects parity when an AT command is issued.

$EB1 enables an 11-bit format.

&E3 Flow Control Disable

The &E3 command completely disables data flow control initiated by the modem.

&E4 Hardware Flow Control

Factory default. The &E4 command enables the modem’s use of the Clear to Send (CTS) signal on the RS- 232/V.24 interface to regulate data flow. When CTS drops, data flow is suspended until the signal goes high again. This method of flow control works in conjunction with pacing (i.e., computer-initiated flow control), which uses the Request to Send (RTS) signal on the RS-232/V.24 interface. Hardware flow control cannot be enabled unless an active error correction protocol is selected.

&E5 XON/XOFF Flow Control

XON/XOFF flow control is an in-band method of data flow regulation used by the modem or computer (i.e., by flow control or pacing). If you issue the &E5 command to the modem, it will respond to XON/XOFF pacing, and use XON/XOFF characters as its own method of flow control to the computer.

In-band data regulation means that the XON and XOFF characters (^Q and ^S, respectively) are inserted into the stream of data rather than using separate control lines. When an XOFF character is detected, the data stream is suspended until an XON character is detected. The drawback to using this method of pacing is that some files may contain these characters. If such a file is transferred using a modem, the file transfer can be suspended indefinitely.

&En XON/XOFF Pass-Through

n = 6 or 7 Default: &E6

When XON/XOFF pacing is active, the local modem has two options regarding the XON and XOFF characters. It can respond to and discard the characters from the computer, or it can respond to the characters and pass them through the datacomm link to the remote modem, thereby pacing the remote modem as well.

&E6 causes the modem to respond to and discard the XON and XOFF characters.

&E7 causes the modem to respond to the characters and pass them through the data link to the receiving modem.

&En Hewlett Packard ENQ/ACK Pacing

n = 8 or 9 Default: &E8

If the MT3334HD8 is used with Hewlett Packard (or compatible) equipment, it can be configured to respond to ENQ/ACK pacing as a complement to any other form of active flow control or pacing. In that case, pacing from the Hewlett Packard equipment is processed according to the HP protocol.

&E8 causes the modem to ignore ENQ/ACK pacing.

&E9 causes the modem to respond to the ENQ (^E) and ACK (^F) characters.

&En Non-Error Correction Mode Flow Control

n = 10 or 11 Default: &E10

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