25
Serial commands
In case that data acquisition software PromoLog is not used for reading data from the device, then
following serial commands can be used to read data from the device.
Following commands are usable for reading fl ash memory. Different protocols are fully explained in
their own chapters, here is quick summary of each protocols available commands.
Nokeval SCL protocol
Reading with Nopsa command over SCL protocol.
Modbus RTU protocol
Reading with Nopsa command over Modbus protocol.
Nokeval Nopsa commands (transport protocol SCL or Modbus RTU)
4/16 (Read fl ash from location)
Read data from given location
4/17 (Find time from fl ash)
Give location from fl ash which has newer data than given
time
4/18 (Give fl ash write position)
Give location where fl ash write is progressing
4/19 (Give fl ash size)
Read fl ash size
4/48 (Clock set)
Set new time for the device
4/49 (Clock fetch)
Read time from the device
When reading the memory you have to read faster than what is maximum fi ll rate to be on the safe
side. Command which fi nds time from the fl ash also automatically give a safety margin to the write
position if needed. This safety margin is at least one full sector which means 64kB of data, since data
is always deleted as a full sector at a time.
Radio specifi cations require that no more than 4 data packets can be received in a second on average,
because otherwise duty cycle requirements would not be met. If data is written as unprocessed to
the memory, then memory fi ll rate would be 4x17=68 bytes/s maximum. Lets calculate 65535 bytes
/ 68 bytes/s = 963s = 16min. So if one sector of data is read faster than this then there is no way
that data is deleted before it can be read. In theory memory fi ll rate can be higher than this if interval
logging is used for high number of channels, with very tight interval, but that is not a very feasible
confi guration.
