Campbell Scientific SM4M/SM16M Storage Modules - Manual (Page 9)

Section 1. SM4M/SM16M Storage Module Overview
1-3
The SM4M and SM16M are identical except for the amount of memory they
contain. The internal memory is split into 64 kb blocks. There are 64 blocks
of memory in an SM4M and 256 blocks in an SM16M. This equates to a
capacity of more than 2 million low-resolution storage values for the SM4M
and more than 8 million low-resolution values for the SM16M (see Section
4.4).
1.3 Power
1.3.1 Primary Power
The Storage Module is powered by 5 VDC received from the datalogger or
from data retrieval interfaces such as the SC532(A) 9-pin Peripheral to RS232.
Pin 1 of the 9-pin D-connector supplies the 5 VDC. Pin 2 is both the power
ground and signal ground.
1.3.2 Backup Power and Data Retention
The modules use non-volatile flash EEPROM memory which does not require
power to retain data. There is no internal battery.
The flash memory will retain stored data for approximately 10 years.
Typically, the flash memory can be erased and rewritten a minimum of
100,000 times.
1.4 Function
The SM4M and SM16M Storage Modules supplement the storage capacity in a
datalogger. The Storage Modules can store data from Campbell Scientific
dataloggers and from other devices which properly enable them.
All Storage Module operations occur in one of three basic operational modes:
1. Interactive communication with the datalogger for data and program
storage and retrieval.
2. The Printer-Enable Method for data storage with the 21X and CR7, with
older operating systems, and also with the DSP4.
3. The Telecommunications Command State for data retrieval and other
miscellaneous operations.
1.4.1 Operation with Current Dataloggers
The Storage Module uses an interactive command structure with handshaking
when connected to the CR500/510, the CR10/10X, CR23X, or to the 21X or
CR7 fitted with recent software (see Figure 1-2). If the Storage Module is not
connected the datalogger does not send data. The datalogger detects when the
Storage Module is connected and sends the backlogged data the next time it
executes Instruction 96.