Campbell Scientific SM192/SM716 Storage Modules - Manual (Page 26)

C-1
APPENDIX C. NON-DATALOGGER APPLICATIONS
All non-datalogger Storage Module operations
are accomplished through the Printer Enable
Method. The Storage Module can store data
from devices other than dataloggers and
computers providing that power and control
requirements are met. Refer to Section C.3 for
information on the pin configuration for the
Storage Module's 9 pin D connector.
C.1 USING TELECOMMUNICATIONS
COMMANDS TO SEND DATA FROM A
COMPUTER TO STORAGE MODULE
Once communication has been established
between the Storage Module and a computer
(Section 5), the 0/H command stores all data on
the Storage Module's transmit data (TD) line
until the PE (pin 6) and CLK/HS (pin 7) lines go
low. This feature is used to transfer a data file
from the computer to the Storage Module.
External power must remain applied for at least
5 milliseconds following data transmission for
"housekeeping." The SM stores 2 bytes at a
time, so if the total number of bytes transmitted
is an odd number, a NULL character will be
added at the end of the transmission.
NOTE: This command is not available
when using the CR10 as the
telecommunications interface to the
Storage Module.
C.2 OTHER NON-DATALOGGER
DEVICES
The Printer Enable Method (Section 4) is used
for non-datalogger SM applications. The PE
line must be low when power is applied or
removed. If a switch is used to enable data
storage, the switch must be debounced. Figure
C.1 depicts debounced circuitry sufficient for
this purpose:
The user should be aware of 3 cases of
transmitting bytes which have special meaning
to the Storage Module in the Printer Enable
Mode. These cases only apply to non-
datalogger applications.
1. In the 76,800 with 9600 fall back baud rate
option, the byte 80 HEX must not be the first
byte transmitted at 76,800 baud after the PE
line (Pin 6) goes high. As a first byte, 80 HEX
causes the baud rate to falsely be set at 9600
baud. There is no such restriction when
transmitting at other baud rates. Campbell
Scientific Inc. dataloggers never transmit 80
HEX as the first byte.
2. The HEX byte-pair 7C01 is a File Mark. This
sequence should only be used to separate data
in the Storage Module.
3. The binary byte-triplet 01111101
XXXXXXXX 1XXXXXXX (X = unimportant
information), is a control code reserved by the
Storage Module to mark the beginning of a
stored datalogger program. The "0/F"
telecommunication command (Continuous
Binary Dump) can be used to collect files which
contain this code.
NOTE: The precautions described in
Section 4.5, Data Format and Input Buffer,
apply.
FIGURE C.1 Manual Switch Debounce Circuitry