RAD Data comm ASMI-450 operation manual Autobaud Function, Ring Indication RI, Data Set Ready DSR

ASMi-450 Control from the Control Port

AUTOBAUD Function

∙When the node address is 0, the DCD line is always ON (active).

∙When a non-zero node address is used, the DCD line becomes ON (active) when data is detected on the RD line, provided the ASMi-450 recognizes its own address in the data stream.

To simulate DTE operation, the delay between these events can be set by the user (by means of the DCD-DELAY parameter).

Ring Indication (RI)

The RI line is used only with dial-up modems (INT=DTE).

The RI line is normally OFF (inactive), and switches to the ON (active) state when the modem attached to the ASMi-450 CONTROL DCE connector detects an incoming call. See also the DSR line.

Data Set Ready (DSR)

∙Usually, the DSR line is configured to track the DTR line. In this case, if the control port interface is DTE, the DSR line will be set to ON for 5 seconds when the RI line is ON while the DTR line is OFF.

∙If the control port interface is DCE, the DSR line can also be configured to be continuously ON. However, if the DTR line switches to OFF, the DSR line will also switch to OFF for 5 seconds.

In addition, the ASMi-450 always sets DSR OFF (inactive) for 5 seconds when the EXIT command is executed, or the disconnect time-out expires.

When the AUTOBAUD function is enabled, the ASMi-450 can identify the operating data rate of the terminal by analyzing the timing of three consecutive Carriage Return + Line Feed characters (generated by pressing three times the carriage return key). The detected data rate is then used for the current communication session.

The automatic baud rate identification procedure is performed (or repeated) whenever three consecutive carriage returns are received after one of the following events occurs:

∙The DTR line has been switched OFF.

∙The EXIT command has been executed.

∙The idle disconnect time-out expired because no data has been exchanged with the control terminal.

In case one of these events occurred, the ASMi-450 assumes that the current communication session has been terminated. Therefore, when the password protection is enabled, the password must be entered again before the control terminal can resume communication with the ASMi-450.

Note that when SLIP communication is required, the AUTOBAUD function must be disabled.

4-4 ASMi-450 Installation and Operation Manual