SECTION 5. TELECOMMUNICATIONS

Telecommunications is used to retrieve data from Final Storage directly to a computer/terminal and to program the CR10. Any user communication with the CR10 that makes use of a computer or terminal instead of the CR10KD is through Telecommunications.

Telecommunications can take place over a variety of links including:

•Telephone

•Cellular phone

•Radio frequency

•Short haul modem and twisted pair wire

•SC32A and ribbon cable

•Multi-drop interface and coax cable

This section does not cover the technical interface details for any of these links. Those details are covered in Section 6 and in the individual manuals for the devices.

Data retrieval can take place in either ASCII or BINARY. The BINARY format is 5 times more compact than ASCII. The shorter transmission times for binary result in lower long distance costs if the link is telephone and lower power consumption with an RF link. On "noisy" links shorter blocks of data are more likely to get through without interruption.

For more efficient data transfer, binary data retrieval makes use of a signature for error detection. The signature algorithm assures a 99.998% probability that if either the data or its sequence changes, the signature changes.

Campbell Scientific has developed a software package which automates data retrieval and facilitates the programming of Campbell Scientific dataloggers and the handling of data files. This package (PC208) has been designed to meet the most common needs in datalogger support and telecommunications. Therefore, this section does not furnish sufficient detail to write telecommunications software. Appendix C contains some details of binary data transfer and Campbell Scientific's binary data format.

The emphasis of this section is on the commands that a person would use when manually (i.e., keyed in by hand) interrogating or programming the CR10 via a computer/terminal. These commands and the responses to them are sent in the American Standard Code for Information Interchange (ASCII).

The telecommunications commands allow the user to perform several operations including:

•monitor data in Input Storage- review data in Final Storage

•retrieve Final Storage data in either ASCII or BINARY

•open communications with the Storage Module

•remote keyboard programming

The Remote Keyboard State (Section 5.2) allows the user with a computer/terminal to use the same commands as the CR10KD.

5.1TELECOMMUNICATIONS COMMANDS

When a modem/terminal rings the CR10, the CR10 should answer almost immediately. Several carriage returns (CR) must be sent to the CR10 to allow it to set its baud rate to that of the modem/terminal (300, 1200, 9600, or 76,800). Once the baud rate is set, the CR10 will send back the prompt, "*", signaling that it is ready to receive a command.

GENERAL RULES governing the telecommunications commands are as follows:

1.* from datalogger means "ready for command".

2.All commands are of the form: [no.]letter, where the number may or may not be optional.

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