3
REAR PANEL DIP SWITCHES
When viewing the Ditak 8 from the rear, there are two banks of DIP switches
located along the top edge of the PC board. The bank of eight switches to the left
is labeled SWA and the bank of six switches to the right is labeled SWB. All of
the SWA switches and five of the SWB switches are used to select the desired
Timebase. The remaining switch of SWB is used to select Frequency Doubling.
WARNING
: Lithium battery may explode if incinerated.
FREQUENCY DOUBLING
DIP switch SWB 6 is the “Frequency Doubling” switch. When it is in the
“ON” position, frequency doubling is disabled. When set to the “OFF” position,
it is enabled and twice the number of input pulses are registered in the unit. This
doubling of the input rate allows the Timebase Increment Total to be halved,
thus allowing a faster update time for a given display value.
TIMEBASE SELECTION
The Ditak 8 has a Timebase selection range from 3.906 msec to 31.998 sec.
SWA 1 is set to the “ON” position for the minimum Timebase setting. SWA 1
through SWB 5 are set to the “ON” position for the maximum Timebase setting.
A specific Timebase setting is achieved by adding the appropriate individual
Timebase increments.
TIMEBASE
TIMEBASE
SWITCH
INCREMENTS
SWITCH
INCREMENTS
SWA 1
1
SWB 1
256
SWA 2
2
SWB 2
512
SWA 3
4
SWB 3
1024
SWA 4
8
SWB 4
2048
SWA 5
16
SWB 5
4096
SWA 6
32
SWB 6
FREQ. DBL.
SWA 7
64
SWA 8
128
The Timebase increment total is computed according to the following formula:
TIMEBASE INCREMENT TOTAL (TBIT) =
WHERE:
DR
=
Desired Reading
RPM
=
Revolutions Per Minute
PPR
=
Pulses Per Revolution
FQ.DBL.
=
Frequency Doubling disable (times 1 switch on,
times 2 switch off)
Example:
Find the appropriate Timebase DIP switch setting for desired
parameters.
Desired Readout (DR)
= 2500
Revolutions Per Minute (RPM) = 1250
Pulses Per Revolution (PPR)
= 50
FQ.DBL. = ON (times 1 switch on)
TIMEBASE INCREMENT TOTAL (TBIT) =
TBIT = 614.44
TBIT = 614
{round to the nearest whole number}
TBIT = 614
DIP SWB 2
-
512
102
-
Needed
DIP SWA 7
-
64
38
-
Needed
DIP SWA 6
-
32
6
-
Needed
DIP SWA 3
-
4
2
-
Needed
DIP SWA 2
-
2
0
-
Needed
Note: If no timebase switches are turned on, the Ditak 8 will default to 3.906
msec timebase.
DIP switches SWA 2, 3, 6, 7, and SWB 2 are all set to the “ON” position for
a Timebase Increment Total of 614. If it is desired to know what the
approximate Timebase is in seconds, use the following formula:
TBIT x 0.003906
=
Time in seconds
614 x 0.003906
=
2.398 sec.
2500 x 15,361
1250 x 50 x 1
DR x 15,361
RPM x PPR x FQ.DBL.
TYPICAL APPLICATION
CONVEYOR BELT SPEED INDICATOR
It is desired to display the rate of a conveyor belt used to carry PC Boards through an infrared soldering chamber that is variable from 0 to 10 feet per minute.
The rate must be adjusted depending on the size of the boards being soldered. The display of the rate indicator must read in feet per minute. The shaft of the variable
speed motor contains a keyway. A speed of 100 RPM will produce a belt speed of 10 ft/min. A proximity sensor is used to monitor the speed of the shaft. The Ditak
8 can be used to display the belt speed in this application. The output signal of the sensor is connected to the Ditak 8 Terminal 3 (INP). The sensor common and
shield are connected to the Ditak 8 Terminal 1 (GND). The Timebase setting is to be determined by using the formula.
TIMEBASE INCREMENT TOTAL (TBIT) =
=
Desired Reading
= 10
MAX RPM Of Shaft
= 100
Pulses Per Revolution
= 1
FQ.DBL.
= ON (times 1 switch on)
TBIT = 1536.1
TBIT = 1536
{round to the nearest whole number}
TBIT = 1536
DIP SWB 3
- 1024
512
-
Needed
DIP SWB 2
-
512
0
-
Needed
With these DIP switch settings, the Timebase would be approximately 5.99 sec
(1536 x 0.003906 = 5.995). To reduce the display update time, the “Frequency
Doubling” switch can be enabled (set to the “OFF” position). Therefore, only half
the Timebase will be necessary (768 x 0.003906 = 2.99 sec.).
TBIT = 768
DIP SWB 2
-
512
256
-
Needed
DIP SWB 1
-
256
0
-
Needed
DIP SWB 6
-
OFF
-
Frequency Doubling Enabled
10 x 15,361
100 x 1 x 1
DR x 15,361
RPM x PPR x FQ.DBL.
