Spectrum Controls 1769sc-HART Modules - Manual (Page 61)

Chapter 6: Module Data, Status, and Configuration
User’s Manual 0300217-03 Rev. A
6-9
Note: The range of this value is defined by the data format selected for the channel.
6.3.16 Low Clamp Value (Words 4, 12, 20, 28)
The low clamp value determines the minimum analog signal that will be applied to the
associated channel.
Note: If the channel command value
1
is less than or equal to the low clamp value, the
under range status bit, for the associated channel, will be set.
The low clamp value must be less than the high clamp value or a
module fault will be generated. If both the low clamp and high
clamp values are left at zero, the output is clamped using the end
points of the associated channel’s defined output range
6.3.17 High Clamp Value (Words 5, 13, 21, 29)
The high clamp value determines the maximum analog signal that will be applied to the
associated channel.
Note: If the channel command value
1
is greater than or equal to the high clamp value,
the over range status bit, for the associated channel, will be set.
The low clamp value must be less than the high clamp value or a
module fault will be generated. If both the low clamp and high
clamp values are left at zero, the output is clamped using the end
points of the associated channel’s defined output range
6.3.18 Ramp Rate Value (Words 6, 14, 22, 30)
The ramp rate value defines the rate at which the output will change state once a channel
is commanded to a new value. The ramp rate is defined in terms of the selected
range/format in units per second. For example, in the 0 to 20mA DC range and percent
of full scale format, a ramp rate of 1000 is 10%/second or a maximum of 1mADC per
second. The following table describes the minimum ramp rate that can be applied for all
output range/types and output data formats.
Table 6-6 (Minimum Allowed Ramp Rates)
Output Data Format
Output Range/Type
Total Counts in Full
Scale
Number of Counts for
Every 1% of Ramp Rate
Real Units / Second for
Every 1% of Ramp Rate
Proportional Counts
0 to 20mA 65534 655 0.2 mA/Sec
4 to 20mA 65534 655 0.16mA/Sec
Engineering Units
0 to 20mA 21000 210 0.2 mA/Sec
4 to 20mA 17800 178 0.16mA/Sec
Scaled for PID
0 to 20mA 16383 164 0.2 mA/Sec
4 to 20mA 16383 164 0.16mA/Sec
Percent of Full Scale
0 to 20mA 10000 100 0.2 mA/Sec
4 to 20mA 10000 100 0.16mA/Sec
Note: If you enter a ramp rate value that is less than the minimum specified in the
table above, a module fault will be generated.
1 Module output words 0 through 3 for channel 0 through 3, respectively.
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Attention