Spectrum Controls 1746sc-NI8u - Manual (Page 50)

38 SLC 500 ™ Universal Analog Input Module
Select Channel Enable (Bit 0)
Use the channel enable bit to enable a channel. The universal module only
scans those channels that are enabled. To optimize module operation and
minimize throughput times, unused channels should be disabled by setting
the channel enable bit to zero.
When set (1) the channel enable bit is used by the module to read the
configuration word information you have selected. While the enable bit is
set, modification of the configuration word may lengthen the module
update time for one cycle. If any change is made to the configuration
word, the change will be reflected in the status word before new data is
valid (described in the last section of this chapter).
While the channel enable bit is cleared (0), the associated channel data/
status word values are cleared. After the channel enable bit is set, the
associated channel data/status word remains cleared until the universal
module sets the channel status bit (bit 0) in the channel status word.
Select Input Types (Bits 1-5)
The input type bit field lets you configure the channel for the type of input
device you have connected to the module. Valid input devices are types J,
K, T, E, R, S, B, N, and C thermocouple sensors, 100
Ω , 200 Ω , 500 Ω , and
1000 Ω Pt 385 RTDs; 100 Ω , 200 Ω , 500 Ω , and 1000 Ω Pt 3916 RTDs; 10 Ω
Cu 426 RTD, 120 Ω Ni 618 RTD, and 120 Ω Ni 672 RTD sensors; 3000 Ω
resistance devices and ±50mV, ± 100mV, ±500mV, ±2V, 0-5V, 1-5V, 0-
10V, ±10V, 0-20mA, and 4-20mA analog input signals. The channel can
also be configured to read the cold-junction temperature calculated for that
specific channel. When the cold-junction compensation (CJC)
temperature is selected, the channel ignores the physical input signal.
RTD and resistance inputs can only be supported by channels 4-7.
Select Data Format (Bits 6 and 7)
The data format bit field lets you define the expressed format for the
channel data word contained in the module input image. The data types
are engineering units, scaled-for-PID, and proportional counts.
The engineering units allow you to select from two resolutions, x1 or
x10. For engineering units x1, values are expressed in 0.1 degrees,
0.01mV or 0.001mA. For engineering units x10, values are expressed in
1.0 degrees, 1mV or 0.01mA. (Use the x10 setting to produce
temperature readings in whole degrees Celsius or Fahrenheit.) You will
notice in Table 11 that not all input types can support the x1 format.
The scaled-for-PID value is the same for millivolt, milliamp,
thermocouple, RTD, resistance,) and CJC input types. The input signal
range is proportional to your selected input type and scaled into a 0-16,383
range, which is standard to the SLC PID algorithm.