Specifications

OPERATIONS
Page 84 MRC-565 Packet Data Radio Operations & Maintenance
5.8.10 Memory Management
Each time the radio reads data from the CR1000, it saves the last data pointer accessed in the
CR1000’s Final Storage RAM. This is used at the next scheduled update interval to get the next
data values without missing data.
If there is no new data recorded in the Final Storage area when the radio scans then nothing is
transmitted. The radio will try again at the next interval. The interval can be set from 1 to 32767
seconds. A good typical value to use is 30 seconds.
The radio limits the amount of data read from the CR1000 to prevent overflowing its’ transmit
memory queue. Each time a group is read, the available memory is checked, and if it goes below
600 Queue blocks, the radio will stop reading data from the CR1000 until the next scan interval.
As data is transmitted memory will get freed up for the next scan interval. In addition, the radio
is limited to a maximum of 200 messages at a time because of the way it assigns message
numbers to each message. These are limited from 1-200, and cannot be duplicated.
The CR1000, MAXQ, N setting is used to limit the number of group reports input to be less than
or equal to a set limit. For example, if MAXQ is set to 20, each scan will read enough to bring
the total to 20 group reports.
5.8.11 Data Scaling
Two data formats are supported and must agree with the setup of the internal CR1000 program.
Only the low-precision format is currently supported. The CR1000,SCALE,CR1000 option will
use the Campbell Scientific floating point format and assumes the sensors are calibrated in
engineering units within the CR1000.
The CR1000,SCALE,INT format assumes each sensor is calibrated in integer mV, and formats
the data in 2's complement integer Hexadecimal format by truncating the fractional part of the
floating point number. Example: CR1000 outputs 103.7, the radio truncates it to 103, then
converts it to hex 0067. The value -103.7 will be converted to hex FF99. The CR1000 maximum
low-precision values use 13 significant bits where +6999 is converted to hex 1B57 and -6999 is
converted to hex E4A9. The radio uses 16 bits for each sensor data value.
5.8.12 Modem Enable
For applications that require very low power, the CR1000 can go to sleep between operations.
By default the use of the ME line is turned ON and the RING line must be pulled high to wake
up the CR1000. This mode is enabled in the radio by the command: CR1000, MODEM
ENABLE,ON. When the radio wants to communicate with the CR1000, it raises the RING line,
and waits for the CR1000 to raise the ME line. The ME line must be tied to the RTS line of the
radio. Once the ME line is high the radio lowers the RING line and begins its command
sequences. When the last command is completed the CR1000 goes back to sleep.