Campbell Scientific SM4M/SM16M Storage Modules - Manual (Page 16)

Section 2. Storing Data from Current Dataloggers
2-2
previous output, and updates the Storage Module Pointer to the DSP
location. This transfer occurs in binary at 9600 baud.
Under optimum conditions, the datalogger outputs 480 low resolution data
points per second. For example, a full 128K CR10X takes over two minutes to
complete the data transfer. If the execution interval is less than two minutes,
the data transfer will be interrupted and will take longer to complete.
Be sure to complete the data transfer before making any
changes in the datalogger program. Changing a program
and then compiling it will advance the datalogger’s Storage
Module Pointer to the position of the DSP. If this is done
before connecting the Storage Module to allow the
datalogger to transfer the data, the old data will not be
automatically transferred to the Storage Module. Also, the
Instruction 96 data transfer will not take place while the
datalogger is in communication with another device (e.g., a
computer or an active CR10KD).
To be certain that the Storage Module has been connected during an execution
of Instruction 96, you can observe the green “ WRITE” LED of the SM which
indicates when data is being stored into the module. The user should connect
the SM to the datalogger and wait for the green LED to light. When the LED
goes off, data transfer is complete and the SM can be disconnected.
To avoid data loss, data must be retrieved before the datalogger’s ring memory
wraps around and begins to write over the oldest data.
2.1.1 Multiple Storage Modules with the CR500/510, CR10/10X,
or CR23X
These dataloggers use synchronous addressing to communicate with multiple
peripherals. The CR23X must have OS1.7 or later to work with multiple
modules. Up to four SM4M/SM16M Storage Modules can reliably be
connected to a single datalogger. Each is assigned an address, 1 to 8.
Addresses are assigned in the *9 Mode (command 10), using SMS or in the
Telecommunications Command State (the L command). These are discussed
in the datalogger manuals and Appendix B respectively. The default Storage
Module address after Reset (as shipped from the factory) is #1. This will be
sufficient for most users.
While up to eight Storage Modules can be addressed,
communication may be unreliable if more than four SM4M
or SM16M modules are connected to a datalogger at a
time. Contact Campbell Scientific if you need to connect
more than four modules.
At a given time, only one Storage Module will accept commands directed to
SM #1. If there is no Storage Module with address #1, the Storage Module
with the lowest numbered address will accept the commands sent to SM #1.
CAUTION
CAUTION