Sierra Wireless DART 200 CDPD Modem manual Modem dial directory, Viewing the IP Address directory

DART 200 CDPD Modem User’s Guide 8 Application Programming

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NOTE: Bigger is not necessarily better when it comes to data transfer block sizes. Take time to test and analyze your situation for optimum results.

1.If your application involves transmitting relatively large data files, test the data transfer using a variety of block sizes. Begin with the large blocks preferred by your customer. Get some throughput timings and develop an average. If operating in a sniff-and-hop CDPD environment, there can be significant variation in the timings. If CDPD operates on dedicated channels variations are much less.

2.Do enough tests to get a meaningful average. If your application operates at specific times of the day in a sniff-and-hop environment, only test during the times the application normally operates.

3.Start dropping the blocksize and repeating the analysis. A plot of blocksize versus time to complete the file transfer shows a low point somewhere between the extremes. For example, start with a 1200 byte blocksize, and drop it by 200 until you hit 200. Explore the low point; the real low might be at 337 bytes, or 489.

4.Once the best point from a throughput perspective is found, ask your carrier for a protocol trace of the transfer to determine actual byte counts. Again, try several, since variations in timing usually imply variations in byte count. To ensure that the best point also has the lowest byte counts, trace some tests with larger and smaller blocksizes.

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NOTE:

Entries do not need to be sequential, and port numbers are not required (except for dial addresses). Also, having a port number does not prevent an entry from being used for pinging or as a friendly address.

Modem dial directory

To help minimize entering IP Addresses, which with port numbers can be quite long, the DART 200 offers a dial directory to store up to 10 entries. Refer to &Z command in Appendix F, DART AT Command Set. These addresses are referenced by slot number (0 to 9) and can be used for dialing (ATDTSn or ATDPSn), pinging (AT*PSn), or specifying friendly IP Addresses for the friends only feature.

Make entries with the AT&Zn= command, and view the directory with the AT&Z? command, as shown in Figure 8-1.

Figure 8-1. Viewing the IP Address directory

AT&Z?

&Z0: 166.174.113.27/1200

&Z1: 166.174.44.13

&Z2: 166.174.113.63/2100 &Z3:

&Z4:

&Z5:

&Z6:

&Z7:

&Z8:

&Z9: 166.174.113.31/2100

OK

Sierra Wireless, Inc. 8-24