SECTION 4. STORAGE MODULE MEMORY AND DATA ENCODING
4-2
receiving data plus 110 usec for each byte
remaining in the input buffer after transmission
is complete. As an example, it takes 130 msec
to transmit 1000 bytes at 76,800 baud. The
Storage Module has time to store 619 bytes
(130 msec divided by 210 usec/byte) before the
transmission has ended. That will leave 381
bytes in the input buffer when the PE line drops.
The SM will take 42 msec (381 bytes times 110
usec/byte) plus 5 msec overhead to process
and store the remaining bytes. This results in a
total of 177 msec to receive and store 1000
bytes at 76,800 baud.
Bytes from the Storage Module input buffer are
permanently stored in byte-pairs. The Campbell
Scientific Inc. dataloggers' Final Storage Format
data are always grouped in pairs. Printable
ASCII and general purpose data transmissions
may have a single byte left in the input buffer
when the PE line drops. In this case, the byte is
left in the input buffer until another transmission
occurs. It will be paired with the first byte and
stored in permanent storage with the current
data.
If a single byte remains in the input buffer when
power is disconnected from the Storage
Module, it will be stored with a null character
(ASCII Code O) as the second byte the next
time external power is applied. A File Mark is
stored at power-up. If there is an added null
character, it will be placed before a File Mark.
