Campbell Scientific CR510 Basic Datalogger - Manual (Page 67)

5-1
SECTION 5. TELECOMMUNICATIONS
Telecommunications is used to retrieve data from Final Storage directly to a computer/terminal and to
program the CR510. Any user communication with the CR510 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 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 B 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 CR510 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 and 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.
5.1 TELECOMMUNICATIONS
COMMANDS
When a modem/terminal rings the CR510, the
CR510 should answer almost immediately.
Several carriage returns (CR) must be sent to
the CR510 to allow it to set its baud rate to that
of the modem/terminal (300, 1200, or 9600).
Once the baud rate is set, the CR510 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.
3. Valid characters are the numbers 0-9, the
capital letters A-M, the colon (:), and the
carriage return (CR).