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Section 2. Internal Data Storage
2-3
The
SPTR
is used to control data transmission to a Storage Module. When on-line
transfer is activated by Instruction 96, data is transmitted each time an Output
Array is stored in Final Storage if the Storage Module is connected to the CR10X.
If the Storage Module is not connected, the CR10X does not transmit the data nor
does it advance the SPTR to the new DSP location. It saves the data until the
Storage Module is connected. Then, during the next execution of Instruction 96,
the CR10X outputs all of the data between the SPTR and the DSP and updates the
SPTR to the DSP location (see Section 4.)
The SPTR can also be positioned via the keyboard for manually initiated data
transfer to the Storage Module (*8 Mode).
The
MPTR
is used in transmitting data over a telecommunications interface.
When telecommunications is first entered, the MPTR is set to the same location as
the DSP. Positioning of the MPTR is then controlled by commands from the
external calling device (see Section 5).
The
PPTR
is used to control data transmission to a printer or other serial device.
Whenever on-line printer transfer is activated (using Instruction 96), data between
the PPTR and DSP is transmitted. The PPTR can also be positioned via the
keyboard for manually initiated data transmission (*8 Mode).
All memory pointers are set to the DSP location when the
CR10X compiles a program. For this reason,
always retrieve
uncollected data before making program changes.
2.2 Data Output Format and Range Limits
Data is stored internally in Campbell Scientific’s Binary Final Storage Format (see
Appendix C). Data can be sent to Final Storage in either low resolution or high
resolution format.
2.2.1 Resolution and Range Limits
Low resolution data is a 2-byte format with four significant digits and a maximum
magnitude of +6999. High resolution data is a 4-byte format with five significant
digits and a maximum possible output value of +99999 (see Table
2-1).
Table 2-1 Resolution Range Limits of CR10X Data
Minimum
Maximum
Resolution
Zero
Magnitude
Magnitude
Low
0.000
+0.001
+6999.
High
0.0000
+0.00001
+99999.
The resolution of the low resolution format is reduced to three significant digits
when the first (left most) digit is seven or greater. Thus, it may be necessary to use
high resolution output or an offset to maintain the desired resolution of a
measurement. For example, if water level is to be measured and output to the
nearest 0.01cm, the level must be less than 70cm for low resolution output to
display the 0.01cm increment. If the water level was expected to range from 50 to
80cm the data could either be output in high resolution or could be offset by
20cm (transforming the range to 30 to 50cm).
CAUTION