Specifications

Setup & SetUp Command 5-9
Byte 4
This setup byte specifies the number of displayed digits and the digital filter
time constants.
Number of displayed digits
For ease of use, the data outputs of all modules are standardized to a
common 7-digit output consisting of sign, 5 digits, decimal point, and two
more digits. Typical output data looks like: +00100.00. However, best-case
resolution of the A/D converter is 1 part in 32,768. In some cases, the
resolution of the output format is much greater than the resolution of the
measurement system. In such cases, the trailing digits of the response
would display meaningless information. Bits 6 and 7 are used to insert
trailing zeros into the output data to limit the output resolution and mask off
meaningless digits.
Bit 7 Bit 6
0 0 XXXX0.00 (4 displayed digits)
0 1 XXXXX.00 (5 displayed digits)
1 0 XXXXX.X0 (6 displayed digits)
1 1 XXXXX.XX (7 displayed digits)
For example, the D1411 model for RTD’s has 0.1 degree output resolution.
The appropriate number of digits for this module is 6, to mask off the 0.01
digit which has no meaningful data. In some cases, the user may want to limit
the output resolution to 1 degree. To do this, select bits 6 and 7 to display
5 digits. With this selection, the right-most two digits will always be set to ‘0’.
The number of displayed digits affects only data received from an RD or ND
command.
Large Signal Filter, Bits 3,4,5
Small Signal Filter, Bits 0,1,2
The modules contain a versatile single-pole, low-pass digital filter to smooth
out unwanted noise caused by interference or small signal variations. The
digital filter offers many advantages over traditional analog filters. The
filtering action is done completely in firmware and is not affected by
component drifts, offsets, and circuit noise typically found in analog filters.
The filter time constant is programmable through the SetUp (SU) command
and can be changed at any time, even if the module is remote from the host.
The digital filter features separate time constants for large and small signal
variations. The Large Signal Filter time constant is controlled by bits 3,4,5.
This time constant is used when large signal variations are present on the
input. The Small Signal Filter time constant is controlled by bits 0,1,2. This
filter time constant is automatically selected when input signal variations are
small. The microprocessor in the module automatically selects the correct