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APPENDIX A How to Specify Systems with Digital Outputs
A.1 General
To order a transducer with digital output, you must first determine the stroke length, the resolution, and
the maximum acceptable update time for your application, and then select the appropriate options. Four
sizing procedures are provided:
I. Natural Binary Output, using the standard 27-28 MHz clock.
II. Natural Binary Output, using non-standard clocks.
III. BCD Output, using the standard 27-28 MHz clock.
IV. BCD Output, using non-standard clocks.
Note that procedures I and III, based upon a 27-28 MHz counter card clock crystal, offer a scaled output
with the standard shipping schedule. If the combinations of options available do not match the resolution
or update needs of your application, MTS Sensors Division can (by special order) modify the clock crystal
rate to improve resolution or shorten update time. Refer to procedures II and IV to select a non-standard
counter card clock crystal.
A.2 Natural Binary Output Selection
PROCEDURE I
System Sizing for Natural Binary Output (Scaled Output, 27-28 MHz Clock Crystal)
This procedure is for 95% of all applications, and provides a scaled output with best possible
manufacturing lead time. (For applications requiring a shorter update time or a non-standard reso-
lution, use procedure II.) From the stroke length, resolution, and maximum acceptable update
time, we can determined the number of TTL level parallel bits supplied by the Digital Counter
Card(s), the number of circulations required in the Digital Personality Module (or Digital Interface
Box), and the actual update time using a standard 27 MHz clock crystal.
Take the following steps:
1. Divide the stroke length by the resolution. This number gives the minimum number of counts
required. Use Table 1A to determine how many bits are required to accommodate this number.
2. Use Table 2A to determine how many circulations are required for the specified resolution.
3. Use the graph in Figure A-1 to determine the update time, based upon the stroke and circula-
tions.
NOTE:
The following additional steps are recom-
mended, to increase output stability:
a. Divide the required resolution by 2
b. Select the number of bits from Table
1A, using the new resolution.
c. Discard or do not connect to the least
significant bit.
d. Do not exceed 18 bits (to avoid using
an additional counter card.)
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