Campbell Scientific SM192/SM716 Storage Modules - Manual (Page 6)

SECTION 1. SM192/716 STORAGE MODULE OVERVIEW
1-2
FIGURE 1.2-1. Storage Module and SC12 Cable
1.2 PHYSICAL DESCRIPTION
The Storage Module is housed in a sealed
stainless steel canister with a single 9-pin D-
connector. The Storage Module is connected to
a datalogger via the SC12 9-Pin Peripheral
Cable.
The SM192 and SM716 are identical except for
the amount of memory they contain. The
SM192 has a CPU card with six 32k RAM chips,
providing 192,896 bytes of storage. The SM716
contains the CPU card plus a memory
extension card with 16 additional 32k RAM
chips. Total storage capacity in the SM716 is
716,672 bytes.
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, 9-pin
Peripheral to RS232 Interface, the SM232A
Storage Module - RS232 Interface, or the
PC201 Clock-SIO Tape Read Card. 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
Memory backup power is provided by an
internal 3.5 VDC lithium thionyl chloride battery
when the Storage Module is disconnected from
a primary power source. About 6 years of RAM
backup power can be expected from the lithium
battery at room temperature. Higher
temperatures increase the current drain of the
RAM chips and the self-discharge rate of the
battery while lower temperatures decrease the
battery's capacity, i.e., energy. At 50oC, battery
life will be about 2 years; at -25oC, about 4
years can be expected. If possible, keep the
Storage Module at or near room temperature
when not in use.