Chapter 5
Channel Configuration, Data, and Status
5–2
The channel configuration word consists of bit fields, the settings of which
determine how the channel operates. This procedure looks at each bit field
separately and helps you configure a channel for operation. Refer to
Table 5.A and the bit field descriptions that follow for complete
configuration information. Page iv contains a configuration worksheet that
can assist your channel configuration.
Configure Each Channel
1. Determine the input device type (RTD type or resistance input) for a
channel and enter its respective 4–digit binary code in bit field 0–3 (Input
Type Selection) of the channel configuration word.
2. Select a data format for the data word value. Your selection determines
how the analog input value from the A/D converter will be expressed in
the data word. Enter your 2–digit binary code in bit field 4–5 (Data
Format Selection) of the channel configuration word. Depending upon
how you configure these bit settings, you may have to select a user–set
scaling range. An example on page 5–15 (user–set scaling) explains how
to do this.
3. Determine the desired state for the channel data word if a broken input
condition is detected for that channel (open circuit or short circuit). Enter
the 2–digit binary code in bit field 6–7 (Broken Input Selection) of the
channel configuration word.
4. If the channel is configured for RTD inputs and engineering units data
format, determine if you want the channel data word to read in degrees
Fahrenheit or degrees Celsius and enter a one or a zero in bit 8
(Temperature Units) of the configuration word. If the channel is
configured for a resistance input, this field is ignored.
5. Determine the desired input filter frequency for the channel and enter the
2–digit binary code in bit field 9–10 (Filter Frequency Selection) of the
channel configuration word. A lower filter frequency increases the
channel update time, but also increases the noise rejection and channel
resolution. A higher filter frequency decreases the channel update time,
but also decreases the noise rejection and channel resolution.
6. Determine which channels are used in your program and enable them.
Place a one in bit 11 (channel Enable) if the channel is to be used. Place a
zero in bit 11 if the channel will not be used.
7. Select the excitation current for the input channel. A zero in bit 12
provides an excitation current of 2.0 mA; a 1 provides 0.5 mA. Select the
excitation current value based on RTD vendor recommendations and the
Input Specifications table, page ii.
8. If you have chosen proportional counts data format, select whether you
want the module–defined default scaling selected for each channel or if
you want to define the scaling range yourself. Use bits 13 and 14
(user–set scaling) for this setting. If you choose to define the scaling
range for proportional counts data format, make sure to enter the lower
Channel Configuration
Procedure
AB Spares
Summary of Contents for SLC 500 1746-NR4
Page 1: ...User Manual SLC 500t RTD Resistance Input Module Cat No 1746 NR4 Allen Bradley AB Spares ...
Page 15: ...Preface P 8 Notes AB Spares ...
Page 37: ...Chapter 2 Quick Start 2 12 Notes AB Spares ...
Page 63: ...Chapter 4 Preliminary Operating Considerations 4 12 Notes AB Spares ...
Page 87: ...Chapter 5 Channel Configuration Data and Status 5 24 Notes AB Spares ...
Page 107: ...Chapter 7 Module Diagnostics and Troubleshooting 7 8 Notes AB Spares ...
Page 117: ...Chapter 8 Application Examples 8 10 Notes AB Spares ...
Page 123: ...Appendix A Specifications A 6 Notes AB Spares ...
Page 125: ...Appendix B RTD Standards B 2 Notes AB Spares ...
