Delta RMC151 - Manual (Page 190)

RMC70/150 and RMCTools User Manual
• Verify that the Plot ID register 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. Check the Samples Uploaded Register
Verify that the Samples Uploaded register is not zero. If it is, there is not enough
captured data to fulfill the request. Repeat steps b, c, and d until the Samples
Uploaded register is non-zero.
e. Copy Plot Data to Buffer
Before the next read, you should, of course, copy the data you just read to a plot
buffer.
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.
Tip:
In order to use the plot data, you will probably need to know the sample period. The Sample
Period register contains that information.
Method 4: Read A Continuous Plot (Trending) - Newest Data
Use this method to read plot data continuously. This method captures data whether or
not the data causes an overlap or gap with the last data that was read.
To use this method, the plot should be continuously capturing. To set the plot to
continuously capture, issue the Rearm Plot (103) command and do not trigger or start the
plot. Important: You must disable the plot's automatic trigger in the Plot Template
Editor.
This method uses the Dynamic Plot Upload Area registers.
To read a plot using this method, follow these steps:
1. Verify that the Plot is Continuously Capturing.
Use the Plot State register to tell whether the plot is continuously capturing. The plot
is continuously capturing when the Plot State register is 0:
0 = not triggered, 1 = capturing, 2 = complete.
2. Write 3 to the Upload Mode/Status Register
Write a value of three (3) to the Upload Mode/Status Register. This sets the upload
mode to "continuous-always newest" and resets the Current Index register to zero.
The Current Index register indicates which sample number of the plot the last read
started at. In continuous mode, the Current Index may become very large. It is a 32-
bit number and will wrap when it reaches its limit.
3. Write the Requested Read Samples per Data Set
Write the number of samples per data set that you would like returned per read to the
Requested Read Samples register. The minimum length of the read itself will be
affected by this value, as described later.
170 Delta Computer Systems, Inc.