Sierra Wireless DART 300 manual Troubleshooting, General Communication Problems

13. Troubleshooting

13.1. Introduction

The DART 300 is thoroughly inspected during manufacturing. There are no end-user access items within the case of the modem. If problems occur, check the following table. Some solutions to common problems are described here. General problems communicating with the modem are in the first section and issues that are specific to particular modes in subsequent sections.

If you cannot resolve a problem after reading this chapter and consulting our web site, please contact Sierra Wireless technical support at 877-231-1144 (toll free in Canada and the US) or 604-231-1128 (worldwide) between 06:00 and 17:00 Pacific Time, or e-mail us at support@sierrawireless.com.

13.2. General Communication Problems

Problem Description	Suggestions
Registers but data transfer	Check that packet forwarding conditions are properly set (forwarding
fails.	character and use, inter-character timer, and buffer length) and a
	forwarding event is happening.
	Check that the local host is not inadvertently sending an escape
	sequence (TIES and TDES). Disable the sequence if necessary.
	Check that the host serial cable is properly attached.
	There may be a flow control problem. Verify that RTS and DTR are
	present at the DART 300 and are being asserted. See Section 10.3.
Modem will not answer on	The modem is not closing the session with the first calling client. If
second and subsequent calls.	UDP is being used, set the Server Receive Lock (+WS217) to a suitable
	duration.
	Set a PAD Session Idle Timeout (S30) to a suitable duration.
Modem disconnects	Ensure the DTR signal is not floating or being changed by the host.
intermittently.	Set AT&D0 to have the modem ignore DTR for data state escape.
	Check the setting of the PAD session timer (S30). If data flow is
	interrupted or has breaks greater than the timer, this can expire and
	close the connection.
Data is intermittently lost	Ensure that proper flow control is being used at all connections.
during the connection.	If UDP is used, remember that data delivery is not guaranteed by the
	protocol. Implement a positive acknowledge, sequence check, and a
	timeout scheme at the application level with re-transmissions as needed.
	There may be a problem with CDPD reception at the site causing the
	modem to lose registration. Check the antenna and connections, and
	verify signal strength using +WPRSSI. The signal strength can be
	checked remotely using the GroupWatcher application from Sierra
	Wireless.

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