3
INPUT SET-UP
The selection of input set-up is accomplished by the first three DIP switches,
located along the side of the unit. DIP switches 1-3 are used to configure the
input. Each of these switches are discussed below.
Note: Rate type indicators frequently use magnetic pickups for input devices.
Consequently, there are basic differences between counter and rate-indicator
input circuits. In the Model APLPT/PBLPT input circuit, the hysteresis level
is quite small and the bias levels are significantly different to accommodate
both magnetic pickup inputs, as well as the +5 V and higher logic levels. The
APLPT/PBLPT can work with switch contact closures because of the low
count rate capability. S1 should be closed when switch contact closures are
used as inputs to the unit.
S1 - ON [MAG.PKUP.]: Connects a 0.1µf damping input capacitor from input
to common. This capacitor is commonly used with magnetic pickup
inputs and serves to filter out high frequency noise. It can also be used
to filter switch contact closures.
Note: If excessive contact “bounce” or system “noise” is encountered, an
additional external filter capacitor may be necessary. Reed switches,
mercury wetted contacts, snap action limit switches, and silver alloy
relay contacts with wiping action are usually satisfactory for generating
count input signals. Motor starter contacts, tungsten contacts, and brush
type contacts should not be used.
S2 - ON [LOGIC]: Sets the bias reference so that input logic signals trigger
count pulses as they cross a level of approximately +2.5 V.
OFF: Sets the bias reference so that a signal of 150 millivolts or more will
trigger count pulses. This provides the sensitivity required for low speed
magnetic pickup sensors.
Note: Hysteresis for both S2 “ON” and “OFF” conditions is about 25
millivolts. This means the difference between V
IL
and V
IH
with logic
inputs (S2) is almost insignificant and only a very small signal swing
about the 2.5 V bias level will trigger the input.
S3 - ON [NPN O.C.]: Connects a 3.9 K pull-up load resistor for sensors or
circuits with current sink outputs. Sensor output must sink 4 mA @ V
OL
of 1V or less.
SCALE MULTIPLIER SELECTION
The selection of the scale multiplier value is
accomplished by DIP switches 4 and 5. The table
at right shows what combination of switches is
needed to obtain the desired value.
MODE SELECT
(Decimal Point Selection For 9999 unit only)
The selection of a decimal point location using
DIP switches 7 and 8 is shown in the table at right.
(This feature is available only on the
APLPT4/PBLPT4.) In the APLPT4/PBLPT4, the
proper DIP switches must be selected before the
unit is powered up. To change a decimal point
location, the unit must be powered down, the DIP
switches changed, then powered up. The decimal
point will appear as soon as the display reappears.
MOVING WINDOW AVERAGING AND SELF-TEST
DIP switch 6, the S.T./AVG. switch, serves a dual function of disabling or
enabling the “moving window average” (MWA) function and the self-test
function. When the switch is up, MWA and self-test are both disabled. When the
switch is down, MWA and self-test are both enabled.
MOVING WINDOW AVERAGING
This allows the unit to “collect” and average the last eight input pulses which
is continually updated whenever a new pulse occurs. The oldest input data is
discarded and replaced with the new input data.
SELF-TEST
This unit has a built-in self-test feature which can only be activated
immediately after power-up (the unit will not measure time while in self-test).
To activate self-test, set the S.T./AVG. DIP switch (D.S. 6) to the enable
position. Then apply power to the unit. With this test, all digits are cycled
through starting with a string of zeros. This will be shown for about half a
second, then a string of ones will appear for about the same time duration.
Following these, a string of twos and so on, up to nines will be displayed. After
the nines are shown, a string of decimal points will appear. Next, an interlace
pattern of 1, 0, 1, 0, (1, 0,) then 1, 2, 1, 2, (1, 2,) and so on, until all digits from
zero to nine have been displayed.
The next portion of self-test will display four groups of zeros and/or ones.
(The first two digits from the left, in each group, will always show zeros if it is
an APLPT5/PBLPT5. If it is an APLPT4/PBLPT4, the first two digits will be
blank.) In the first group, the third digit represents the 13th (X4096) DIP switch
setting. The fourth and fifth digits show the setting for the Scale Multiplier
select DIP switches. (The fourth position digit represents DIP switch 4 and the
fifth position digit represents DIP switch 5.) The state of these digits coincides
with the table listed under the “Scale Multiplier Selection” section. The last
digit will always show a one for the APLPT5/PBLPT5. But for the
APLPT4/PBLPT4, if both switches 7 and 8 are off, it will then display a zero.
The next three groups are shown
on the right, and correspond to the
DIP switch shown directly above it.
(Note: The first two digits in each
group are always shown as zeros
or blanks.)
The X’s represent a zero or one (depending on the setting of the DIP switch)
in the display. Self-test is automatically exited 8 seconds after the last DIP
switch is changed.
9 10 11 12
(DIP SWITCH)
Group 2: 0 0 X X X X
5 6 7 8
(DIP SWITCH)
Group 3:
0 0 X X X X
1 2 3 4
(DIP SWITCH)
Group 4:
0 0 X X X X
1000
↑ (1)↑ (1)
100
↑ (1)↓ (0)
10
↓ (0)↑ (1)
1
↓ (0)↓ (0)
SCALE
MULTIPLIER
SW 5SW 4
SW 7 SW 8
D.P.
LOCATION
0
↓ (0)↓ (0)
↑ (1) ↓ (0)
0.0
0.00
↑ (1)↓ (0)
↑ (1) ↑ (1)
0.00
