Rohde & Schwarz Hameg HMO3522, Руководство пользователя

Страница: 30 / 36

30
Subject to change without notice
11 Mixed Signal Operation (optional)
All HMO352x series instruments are provided with the con-
nectors for the HO3508 logic probes necessary to add 8 or 16
digital logic channels. The fi rmware required for Mixed Signal
operation is already contained in each HMO352x, only the
HO3508 active logic probes need to be bought and connected.
With the 4-channel oscilloscope HMO3524 activation of Pod1
will deactivate the analog channel 3, and activation of Pod2 will
deactivate the analog channel 4. Hence these confi gurations
are possible: 3 analog channels plus 8 digital logic channels
(Channels 1,2,4 and Pod1) or 2 analog channels with 16 digital
logic channels (Channels 1,2 plus Pod1 plus Pod2).
With the 2-channel instruments HMO3522 either 2 analog
channels plus 8 logic channels or or 2 analog channels plus 16
logic channels are possible.
11.1. Logic trigger
STOP
You may test all the settings without a logic pro-
be connected, however, the functions will only be
effective with a HO3508 probe connected.
By selecting LOGIC trigger in the soft menu after pushing the
key TYPE the trigger source will be routed to the digital logic
inputs. If you now push the key SOURCE, a soft menu will open
up which offers further settings and a window for a display.
(refer to Fig. 11.1).
The top soft menu is used to preselect the logic channel for
which the trigger condition is to be defi ned. This is done with
the universal knob. The selected digital input will be marked
with a blue background in the general menu; in the fi eld the
trigger level (high) H or (low) L or (any) X will be indicated.
The selection of the logic level is done with the respective soft
menu key. The selected level will also be marked with a blue
background in the soft menu. Another menu selects the logic
combination of the digital logic inputs; they can be combined by
logic AND, OR. If AND is selected, then both conditions must be
met simultaneously for the result to go high H. If OR is selected
either one or both conditions must be met. The last item in this
menu is called
TRIGGER ON . With the soft menu key TRUE or
FALSE can be chosen. This allows you to preselect whether the
trigger shall be generated at the beginning (TRUE) or the end
(„FALSE“) of the logic condition.
Fig. 11.1: Logic trigger menu
M i x e d S i g n a l O p e r a t i o n
After selecting the desired set of conditions, you may push
FILTER for more settings. A soft menu will have opened which
allows you to limit the trigger TRUE condition further in time
(in this menu that condition will appear which you choose in the
SOURCE menu). A time limit can be added by pushing the top
soft menu key. The reference criterion can be selected in the
menu fi eld below by the respective soft key.
These 6 criteria are available:
ti ≠ t: The duration of the bit pattern which will generate the
trigger is unequal to the reference time.
ti = t: The duration of the bit pattern which will generate the
trigger is equal to the reference time.
ti < t: The duration of the bit pattern which will generate the
trigger is smaller than the reference time..
ti > t: The duration of the bit pattern which will generate the
trigger is greater than the reference time.
t
1
< ti < t
2
:The duration of the bit pattern which will generate the
trigger is smaller than the reference width t
2
and greater
than the reference width t
1
.
not(t
1
<
ti
<
t
2
):The duration of the bit pattern which will generate
the trigger is greater than the reference width t
2
and
smaller than the reference width t
1
.
By the same procedure as with pulse trigger the reference time
is adjusted with
ti ≠ t and ti = t by turning the universal knob after
pushing the soft key next to TIME. By selecting DEVIATION the
universal knob allows you to defi ne a tolerance interval. If ti
< t
or ti > t was chosen only one limit may be set. Both options with
two references (t
1
and t
2
) can be set due to pressing the respective
soft key and turning the universal knob.
If you desire to change the levels for logic ONE or ZERO you will
have to choose the channel menu. Select the appropriate POD
(POD1 with the key CH3/POD, POD2 with the key CH4/POD2).
If the logic mode was already selected, you will see the digital
logic channels, and the display will show in its channel infor-
mation section the framed message: „POD1:xxxV“ or „POD2:
xxxV“. If information about the analog channels 3 and 4 should
be shown there, push the key next to the lowest soft menu entry
(before pushing the key it will read: „POD1“ or „POD2“). This
will activate the digital channels. If you now push the key MENU
in the „Channel Control“ section of the front panel, you will be
able to select from 5 predefi ned logic levels, three of them are
fi xed for TTL, CMOS, and ECL, two are user defi nable and may
be set from –2 V to +8 V with the universal knob after pushing
the respective key.
11.2. Display functions of the logic channels
With the HMO352x the short menu in the channel settings is
used to switch an analog channel to a digital channel. If e.g.
the channel 3 was selected, its short menu will be shown: the
lowest soft menu key is entitled POD1. Push this soft menu
key to activate the digital channels. Now the digital channels
0 to 7 will be shown, the short menu will change such that their
important settings can now be selected. In order to return to
the analog channel push the lowest soft menu key.
With the logic channels, a logic ONE will be indicated by a bar
of two pixels width, a logic ZERO will be one pixel wide. The
information fi eld in the lower left corner of the screen will show
the actual sampling rate and the logic levels selected next to
the names POD1 and POD2.