Hardware manual

5901 High Speed Dialup Modem Hardware Manual

October 19, 2007

4.6 5901 Modem Reset Control

A common problem encountered with consumer modems is the tendency to periodically go into an

unstable state. The usual solution for this problem is to simply turn the modem off and then turn it

on again. The modem then returns to normal operation.

When a modem is used in industrial or commercial applications that require it to be installed in very

remote locations this solution is not feasible. The 5901 modem uses a number of methods to ensure

stable operation in virtually all applications.

The 5901 modem is reset to the power up state under any of the following conditions.

 When power is applied from a power off state.

 When the controller RESET signal is active, indicating all I/O modules are to be reset.

 When the DTR signal is low. This is the normal signal from the DTE to reset the modem.

Note: 5901 modem will power up with the default configuration. User entered “AT” commands

are not saved when power is cycled. When a configuration is used that is different than the

default configuration it must be saved to NVRAM in the modem. Refer to the &W0 and

&Y0 commands in Appendix C for more information on saving configurations to NVRAM.

4.6.1 Reset on Power Application

Each time power is applied to the 5901 modem it is reset. Power may be applied to the 5901 modem

in the following ways:

 5VDC applied to the 5901 from the I/O Bus.

 5VDC applied to the 5901 from RS-323 connector pin 9.

 9VDC applied to the 5901 from P5.

4.6.2 Reset on I/O Bus Reset Signal

When the SCADAPack or Micro16 controller RESET signal is TRUE, the modem is turned off and

then turned on. Refer to SCADAPack & Micro16 Hardware manual for information on the

controller RESET signal.

4.6.3 Reset on DTR Control

The 5901 modem will reset when the DTR line in the serial port is de-asserted. The DTE device

connected to the 5901 may control the reset of the 5901 by asserting or de-asserting DTR.

4.6.4 Failure Recovery

If the 5901 modem detects 7 or more rings, in each of two ring attempts within 2 minutes, it will be

reset. This mode allows the user to remotely reset the 5901 modem if failure occurs.

4.7 LED Indicators

The 5901 modem has five status LEDs. These LED’s cannot be disabled to conserve power.

LED

Color

Function

TXD

Red

The TD LED is on when the DTE is transmitting data to the

modem.

RXD

Red

The RD LED is on when data is being received by the modem.