Spectrum Controls 1746sc-INI4vi - Manual (Page 36)

32 SLC 500 ™ Isolated Analog Input Modules
Open Input Circuit Response (configuration bits 7 and 8)
For 1–5 Vdc and 4–20 mA inputs only, use this bit field to define the
state of the channel data word when your module detects an open circuit
for that channel:
• If you select zero on open input circuit, your module sets the channel
data word to zero during an open circuit condition.
• If you select max. on open input circuit, your module sets the
channel data word to its full-scale value during an open circuit.
• If you select min. on open input circuit, your module sets the
channel data word to its low-scale value during an open circuit.
The full-scale and low-scale values (max. and min. count limits) are
determined by the channel’s data format and selected input range. See
Table 14.
Important – If a circuit opens, your module provides input signal values
until it detects and flags the open circuit.
Input Filter Frequency (configuration bits 9 and 10)
Use this bit field to select one of four filters for a channel. The filter
selected affects the channel update time and noise rejection
characteristics:
• A lower filter frequency increases the noise rejection and effective
resolution, but it also increases the channel update time.
• A higher filter frequency decreases the update time, but it also
decreases the noise rejection and effective resolution.
Refer to Chapter 3, Things To Consider Before Using Your Module, for
more information on selecting a filter frequency.
Auto-Calibration Enable (configuration bit 11)
Use this bit to enable or disable auto-calibration. When enabled, auto-
calibration occurs every 10 seconds. Auto-calibration also occurs
whenever you configure a channel (regardless of the setting of this bit).
Unused Bits (configuration bits 12–15)
These bits are not defined. To prevent a configuration error, ensure that
bits 12 through 15 are set to zero.