RF400 Series Spread Spectrum Data Radio/Modems

4.1.3.2 ATDT Command Mode

This mode is not required for basic point-to-point communication.

For point-to-multipoint operation the RF400 can temporarily be put into AT Command Mode by sending a string of three ASCII characters. The default sequence to enter AT Command mode is:

1.No characters sent for one second (before command character)

2.“+++”characters sent (default command mode entry character)

3.No characters sent for one second (after command mode character)

4.RF400 responds by sending “OK” <CR>

The AT Command mode characters are sent by PC208W along with other commands to change the base RF400’s Radio Address to talk to the desired remote RF400 (see point-to-multipoint example in Software Setup Section).

4.1.3.3 Combination Mode Communications

Besides the “direct” to PC communications described in the Quick Start and Installation sections, it is possible to combine methods in datalogger communications. Some examples:

•Phone to RF400: PC to external modem to COM210 w/PS512M to RF400 to datalogger (see Appendix I)

•Short Haul modem to RF400: PC to short haul modems to RF400s to datalogger (see Appendix G)

•Network to RF400: PC to Internet to NL100 to RF400 to datalogger (use LoggerNet IPPort or PC208W socket, remote IP address, port number)

4.1.4Error Handling and Retries

In the RF module received packets are analyzed for data corruption with an embedded CRC. The RF400 rejects a received packet (doesn’t send it out a port) if the packet’s header address fails to match the RF400 address, if an RF module receive error is detected, or if the RF packet’s CRC test fails.

In early RF400s no notification was given when a packet was rejected, and there were no retries nor guaranteed delivery of packets. Retries were handled by protocols in LoggerNet and PC208W. Starting with SW Version 6.420 the RF400 series radios themselves are capable of doing retries in a network with an unlimited number of array-based stations or in a network consisting of two PakBus stations.

4.1.4.1 Standard Retry Levels

There are four pre-programmed Retry Levels available in the Standard Setup menu. All RF400s in the network should be configured for the same Retry Level. The default setting is “None.” The standard settings should satisfy most application requirements. Further choices are available in the Advanced Setup menu. All radios in a network should have the same “Maximum

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