Daqarta for DOS Contents
MEMORY ARRAYS (MemAr):Traces that have been previously saved with MemSv can be shown simultaneously using MemAr. Only "comparable" traces can be displayed this way: They must all have the same number of points N, data format, sample rate, trigger delay, full-scale Y-axis range, and all be averages or all single traces. If they are single traces, they may be mixed waveform or spectrum, since in either case the waveform data is saved, and displayed in whichever mode is current.
The Memory Array control menu can be used to adjust the way the traces are labeled and presented on the screen.
Before you invoke MemAr, you must tell it the lowest trace ID to include by viewing that trace with MemRd. At any time after that, you may hit ALT-M to display the Memory Array. The selected "base" trace and all higher comparable traces will be shown together, up to 32 traces per screen. If there are other traces present that are not comparable with the base trace, they will be ignored no matter where they appear in the original trace numbering sequence.
The selected trace will be in the ususal TRACE color, while the rest will be in the ALT color set via the Main Color control menu. All information such as cursor readouts, comment line, and title line will refer to the selected trace. The values of menu items such as Averager Artifact Limits and Trigger Cycle time will be those of the selected trace.
You can select different traces via ALT-Up/Dn keys, and the relevant information will change. Note, however, that only "internal" parameters have been saved for each trace. Those set from plug-in modules such as the ADC board driver or the STIM3A stimulus generator are not preserved automatically... you may want to use comment field copies to make sure the most important parameters are recorded.
If there are more comparable traces beyond the base trace than allowed by the screen limit, the ALT-Up/Dn keys can be used to scroll the entire screen "window" just by trying to move the selected trace above or below the displayed range.
Alternatively, you can use ALT-PgUp/PgDn to page through the comparable traces in blocks.
While the Memory Array is on-screen, you may use all the same options you could use with a single MemRd trace: You can change the trace magnification, toggle between waveform and FFT modes, Xpand the X-axis, and so on. All traces will be acted upon in unison.
The trace magnification in Memory Array mode is independent of that in normal single-trace mode. This allows you to have a smaller array magnification in order to keep traces from overlapping, yet still keep the original magnification when you return to view a single trace.
Exit from the Memory Array mode by toggling it off with ALT-M, or simply unPause back to a Live trace. Alternatively, MemRd will exit the array and go directly to the individual selected trace.
MEMORY ARRAY FILES:A Memory Array may be saved as one large file by invoking OutDt when the array is on-screen. You may use the File option of the Memory Array control menu to select whether All comparable traces in memory will be included, or only those in the current View.
When later retrieved by InDat, you will have the option of adding the array traces to any others then in memory (if there is room), or of replacing them. Since trace memory IDs are always sequential, the newly loaded traces may not have the same IDs as when originally saved... be sure you can identify each trace from its comment line or some other saved parameter.
If you invoke OutTx while the Memory Array is on-screen, only the selected trace will be sent to the text file.
MEMORY ARRAY CONTROL MENU:Use CTRL-M to bring up the Memory Array control menu at any time. This menu controls the screen presentation as well as the file save protocol for Memory Arrays.
MEMORY ARRAY LABEL:This allows you to select how the array traces will be labeled:
MemID Shows the trace Memory ID as 'Mem N'. Fld # Shows the selected comment field. Off No label shown.
A desired Field number from 1 to 5 may be entered directly. Entering 0 will give MemId, while 6 or above will give Off.
Labels are shown at the right end of each trace, at its relative zero baseline. Waveform trace labels are centered on their baselines, whereas magnitude FFT labels sit just above each zero line. For Y-log FFT traces, the labels are centered on the 0 dB line of each. The labels are shown at these positions even if the corresponding traces come nowhere near their baselines at the right end of the trace. With Y-log FFT traces, it is particularly unlikely that there will be any high-level trace activity at the highest frequencies.
If you have selected 'Fld 1' to 'Fld 5' but there is no text in that field for any given trace, then the memory ID is shown for that trace by default.
This control is completely independent from the Sort control. You can thus sort on one field while labeling with another.
MEMORY ARRAY LABEL WIDTH:If Label is set to one of the comment fields, this controls how much of that field will be used as the label, from 2 characters up to the full field width of 12 characters.
The default setting is 9 characters, which will show most values that have been saved with the field copy option. If the value is an integer, you will see the value including its units prefix and the first two characters of the units label, as in:
If the value is an unsigned decimal, you will see only the first character of the label, since the decimal takes one of the spaces:
'12.345 kH' instead of '12.345 kHz'.
If the value is a signed decimal, you will only see up to the units prefix, as in:
This control affects only the trace labels, not the sorting operation.
MEMORY ARRAY TRACE ORDER:This toggles the order of screen presentation between Up and Down. When set to Up, the traces appear with the lowest sort value trace at the bottom and progress upward to higher values on the screen. (Note, however, that if the Sort control is set differently from the Label control, the actual displayed labels may not be in this order.)
This control only affects the screen, not the operation of selecting or sorting traces. For example, if you have traces 0 through 9 in memory and set the base trace to 5 via MemRd, then when you invoke MemAr you will see traces 5 through 9 displayed. If Sort is set to MemID and Order is set to Up, then trace 5 will be at the bottom and trace 9 at the top. Setting Order to Down simply means that trace 5 will be at the top and 9 at the bottom... it does NOT select traces less than 5.
MEMORY ARRAY DISPLAY LIMIT:This controls the maximum number of traces that may be shown at one time, up to a limit of 32. If there are more traces in the array, you can then scroll or page to them via ALT-Up/Dn or ALT-PgUp/PgDn. This allows you to deal with arrays that would otherwise be too crowded to be viewed all at once.
MEMORY ARRAY SORT:This controls how the traces will be sorted before they are displayed:
MemID Sorted by Memory ID. Fld # Sorted by the selected comment field value. Txt # Sorted by the selected field, treated as text only. Time Sorted by the Trace Time and Date.
You may directly enter the desired value Field number, from 1 to 5. Entering 0 will give MemId. To directly select sorting of a field treated as text only, add 5 to the desired field number: Enter 6 to get Txt 1, or 10 to get Txt 5. Entering 11 or more will select Time.
For Fld 1 to Fld 5 the selected field is treated as a value, including recognition of standard prefixes and signs. This allows a value like '2.3456 mV' to come before '1.2345 V', and also places large negative values before small ones. For example, if Order is set to Up, the following values would be shown on the screen in the left sequence, whereas Txt # would give the right sequence:
Fld # Txt # +1.2345 kV +345.67 µV +23.456 mV +23.456 mV +345.67 µV +1.2345 kV + 0.00 V + 0.00 V -45.678 nV -100.00 kV -5.6789 V -45.678 nV -100.00 kV -5.6789 V
Clearly a simple text-only sort is undesireable in this case. Text sorting should be reserved for non-numeric entries, or where text values are entered manually and don't conform to the standard field-copy format. For example, if you don't use a prefix and don't allow a space for it, the first character of the units label may be interpreted as a prefix and skew the sort. The 'G' in '1.2 Gal' will be seen as a Giga prefix unless you add another space: '1.2 Gal'.
If a Fld # is set for sorting, but one or more traces have improper value formats, those traces will be treated as text and will come AFTER all the proper values:
1 lb ('l' is not a standard prefix) 20 kg 4.34 gIf you save traces sequentially and then display them, the MemID and Time settings will give the same results. But you may store them out of sequence (for whatever reason), or you may build up the array from file traces recorded in different sessions. In either case, the Time option will put them in chronological order.
MEMORY ARRAY STEP:This control allows you to control the vertical spacing between array traces. Its operation changes with the display mode to better fit typical user needs.
For waveform or FFT magnitude displays, a value between 0 and 255 directly sets the number of screen pixels between traces. The entire trace area is 256 pixels tall, but rather than try to compute the step size you will probably want to adjust this by eye. There are two preset conditions that can make things much simpler for most general work:
Equal:If you enter a negative Step value, the Step item will show 'Equal' instead of a number. The trace baselines will be equally spaced, automatically tracking the number of traces present. This is the start-up default and is a good general-purpose setting.
Limit:If you enter a positive value of 256 or more, the Step item will change to 'Limit'. This means the traces will be at the same spacing as though you had Equal here, and the same number of traces present as set by the Limit control. Thus, if you have a predetermined number of traces in a test series, you can keep each trace at a fixed screen position as you build up the series. (TIP: To save a keystroke, enter '1k' instead of '256' to activate this Limit option via direct entry.)
For Y-log FFT traces the Step control sets the spacing between traces in dB, according to the current log range. The range of this control is from 0 to 40 dB per step. The baseline for each trace is taken as its 0 dB line, and each label is shown at that point on the screen, even though there may be no part of the trace anywhere near the 0 dB level at the right end of the trace. This results in a "ranking" of the labels, typically near the upper right of the screen.
Direct Trace Overlap:A Step value of 0 (whether pixels or dB) is particularly useful for comparing traces by direct overlap to see areas of similarity and difference. If you use this method, you may find it best to compare only two traces at a time for clarity. When the two traces happen to be adjacent in the array, you can just set the Limit control to 2 and only those will be shown. But what if they are not adjacent? You may be able in some cases to make them adjacent by changing the Sort method, but in general the most reliable way is to copy both to unused higher memory IDs and reset the array base to see just those two.
If you are really short on trace memory and only have room to copy one trace, you can still pull this off by swapping one of the traces with a trace that is adjacent to the other. You first copy the adjacent trace to the upper memory location, then copy the other trace to the original adjacent spot. Note, however, that when you do this the time record will be updated for each trace saved, as though it was a "new" trace.
If you are going to use the "swap" method, you may want to set the Label and Sort modes to MemID to be sure of the target trace ID and to assure the final sequence.
In either case, use Alt-Up/Dn to select the trace to be copied, hit MemRd to show only that trace, and then hit MemSv and END or the desired target ID. Then go back to MemAr and set the Limit to 2 and the Step to 0.
MEMORY ARRAY POSN or LBL STEP:This control changes its name and entire mode of operation depending on the display mode:
Posn:When waveforms are being displayed, the Posn control allows you to adjust the whole array up or down on the screen. The label for each trace is shown on its baseline, but when the baselines are set too close via the Step control, the label spacing will automatically increase so that the labels don't overlap.
Lbl Step:When magnitude or Y-log FFTs are shown, this is a simple toggle control. It is normally set to Auto, which means that at small Step sizes the label spacing automatically increases just enough to prevent overlap. If you toggle this to Track instead, overlap is allowed.
For waveform display, operation is always in Auto mode.
MEMORY ARRAY FILE:This controls the protocol to be used when saving traces to an Array file with OutDt.
View Saves only the visible traces to the Array file. All Saves all traces in the Array.
When All is selected, the included traces are all those you could display by scrolling or paging through this same array. Traces lower than the base trace (set via MemRd) will not be saved, nor any trace that was not included in the array because it was not comparable to the base trace.
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