Chapter 4 - AT Commands, S-Registers, and Result Codes
&D4 Ignores DTR when answering a data call. If DTR is low when an
| incoming data call is present, the TA will answer the call. If DTR |
| goes high during that call, nothing will happen. However, if DTR |
| goes high and then drops for the minimum time specified by S25, |
| then the call will be disconnected just as it would with &D1. &D4 is |
| the same as &D1, except that &D4 can answer a data call without |
| DTR and DTR can remain low for the duration of the call, but if DTR |
| goes high, then &D4 will behave like &D1. |
Command: &En | |
Function: | Flow Control |
Values: | n = |
Default: | &E4, &E6, &E13 |
Description:Selects method by which the TA controls the flow of data to and from the
| computer to prevent either device from accepting data faster than it can | |
| handle. The TA provides flow control in both directions. When the TA halts | |
| data flow, it is called flow control; when the computer halts data flow, it is | |
| called pacing. | |
| &E3 | Disable flow control by the TA |
| &E4 | Hardware flow control. &E4 causes the TA to use the CTS signal on |
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| pin 5 of the RS232E/V.24 interface to regulate flow control. When |
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| CTS goes low, data flow from the computer is suspended until CTS |
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| goes high again. This method works with pacing, which uses the |
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| RTS signal on pin 4. Hardware flow control cannot be enabled |
|
| unless an error correction protocol is selected. |
| &E5 | XON/XOFF flow control. This is an |
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| XON and XOFF characters (^Q and ^S, respectively) are inserted |
|
| into the data stream, rather than using separate control lines. When |
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| an XOFF character is detected, the data stream is suspended until |
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| an XON character is detected. The drawback to this method is that |
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| some files may contain these characters, causing the file transfer to |
|
| be suspended indefinitely. |
| &E6 | When XON/XOFF pacing is active, TA responds to and discards the |
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| XON/XOFF characters from the computer. |
| &E7 | When XON/XOFF pacing is active, the TA responds to the XON/ |
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| XOFF characters and passes them through the communications link |
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| to the remote device, thereby pacing the remote terminal adapter as |
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| well. |
| &E12 | Disables pacing |
| &E13 | Enables pacing |
Command: #Xn |
| |
Function: | Send Single/Multiple Xoff Characters | |
Values: | n = 0 or 1 | |
Default: | #X0 |
|
Description: Allows TA to send either a single or multiple Xoff characters to exert flow control to the terminal.
The #X0 command (factory default setting) causes one Xoff to be sent until the
#X0
#X1
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