Selecting PIM input threshold
From Control Builder, you can select Low or High voltage thresholds depending upon the sensors
used. Generally, if the sensor outputs a signal in the 0V to 5V range (for example, TTL), the Low
threshold is the best choice. If the sensor’s pulse output is an open collector or open drain type
and the externally supplied Pull-up resistor is used on the IOTA, the High threshold is the best
choice as the signal swings from 0V to about 23V. Other devices that are actively driven require
knowledge of the output swing to determine the proper range. For example, the Swinton
Technology ST500 Dual-Pulse Simulator outputs have a voltage swing of 0V to 12V with respect to
the 0V terminal. Therefore, either the Low or the High threshold can be selected, but there will be
slight difference in the measured Pulse Length (PL) parameter.
ATTENTION
l Millivolt signals are not counted by the PIM unless a suitable preamplifier is used to
boost the signal to a level that can be detected by the PIM circuitry.
l Current Pedestal signaling is not directly supported by PIM circuitry.
The following table lists the typical thresholds for the Low and High ranges.
Input Threshold Setting Trip point for Rising Input
(Low to High transition)
Trip Point for Falling Input
(High to Low transition)
Hysteresis
(typical)
Low 2.75 V 2.04 V 0.71 V
High 8.41 V 7.7 V 0.71 V
Table 6.5 PIM input threshold – Typical low and high ranges
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Chapter 6 - Series C PIM connectivity
Chapter 6 - Series C PIM connectivity
For dependable operation, the sensor signal needs to extend above and below the values
mentioned in the above table to overcome noise and provide significant overdrive.
The following table lists recommended input values for dependable operation.
Input Threshold
Setting
Recommended Signal Level for Rising
Input, Vu
(Low to High transition)
Recommended Signal Level for Falling
Input, VL
(High to Low transition)
Low 3.25 V or more 1.5V or less
High 8.9 V or more 7.2 V or less
Table 6.6 PIM input threshold – Input values for dependable operation
The figure below provides a pictorial representation of the upper and lower trip points and
hysteresis band. For illustration, the rising and falling edges are shown asymmetrically.
Figure 6.24 Illustration of upper and lower trip points and hysteresis band
6.15 Recommended cable types
This section provides recommendations on proper types of external cabling that should be used
with the PIM. Honeywell does not provide PIM interface cables. You must select cables per your
requirements.
The following Belden cable types can be used with PIM.
l Blue Hose Series – 9463, 9463F, 3072F, 89463, 9463DB and so on)
l Brilliance Series (multi-conductor) – 8774
However, you can use similar cables from other manufacturers
