Delta RMC151 - Manual (Page 191)

3 Controller Features
4. Read the Plot Data Starting from Dynamic Plot Upload register #0
Upload Mode 3 will always return the newest data whether or not the data causes an
overlap or gap with the last data that was read. Use the Current Index register to
keep track of the data. The Current Index register indicates which sample number of
the plot the last read started at.
Each time you read the plot data, start the read at Dynamic Plot Upload register #0.
Each read will return Dynamic Plot Upload registers 0-4 and the plot samples
beginning at the sample number in the Current Index register. Since each read
includes registers 0-4, you will have access to the Upload Mode/Status, Current
Index, Plot ID, and Samples Uploaded after each read.
To read the plot data repeat these steps:
a. Calculate the Length of the Read.
The length of the read must be long enough to receive the number of samples per
data set that you wrote to the Requested Read Samples register. In addition to
returning Dynamic Plot Upload registers 0-4, each read will return an equal
number of samples from each data set in the plot. Use the following equation to
calculate the length of the read based on how many samples you wish to read:
length = (Requested Read Samples) x (# of data sets) + 5
The number of samples should not be more the number of samples in the plot.
Typically, you will make this calculation once and then always make reads of the
same length.
b. Read from Dynamic Plot Upload register #0
Read from the Dynamic Plot Upload register #0 with the length calculated in step
a.
c. Do any Error Checking
If you wish, you can use Dynamic Plot Upload registers 0-4 to do error checking,
as described below:
• Verify that the Upload Status is 0, meaning no errors have occurred. If the
Upload Status is 1, the plot has been triggered, completed capturing, and
has been completely uploaded. To recover, issue the Rearm Plot (103)
command to set it to continuous capture.
• Verify that the Plot ID is unchanged. If it has changed, it indicates that you
are no longer reading from the same plot. The plot may have been re-
triggered or reset.
d. Copy Plot Data to Buffer
Before the next read, you should, of course, copy the data you just read to a plot
buffer. Use the Current Index to know where to place the data.
The data is returned in this format:
R
0
, R
1
, R
2
, R
3
,
R
4
A
0
,A
1
,A
2
... A
n-1
B
0
,B
1
,B
2
... B
n-1
C
0
,C
1
,C
2
... C
n-1
D
0
,D
1
,D
2
... D
n-
1
...
where
R
0
= Upload Mode/Status register
R
1
= Requested Read Samples register
R
2
= Current Index register
R
3
= Plot ID register
R
4
= Samples Uploaded register
A = sample from data set 0, B = sample from data set 1, etc.
n = number of samples read per data set.
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