Output image - configuration words, Input image - data words and status words – Rockwell Automation 1746-NR8 SLC 500 RTD/Resistance Input Module User Manual User Manual
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Publication 1746-UM003A-EN-P
3-4 Preliminary Operating Considerations
Output Image - Configuration Words
The RTD module output image (defined as the output from the CPU to the
RTD module) contains information that you configure to define the way a
specific channel on the RTD module works. The 1746-NR8 uses an 8-word
output image when operating in a Class 1 mode and 24-word output image
when operating in Class 3 mode. These words take the place of configuration
DIP switches on the module. Output words 0 through 7 are used to define the
operation of the module; output words 8 through 23 are used for special
user-set scaling using the proportional counts data format. Each output word 0
through 7 configures a single channel.
Example - If you want to configure channel 2 on the RTD module located in
slot 4 in the SLC chassis, your address would be O:4.2.
Chapter 4 gives you detailed bit information about the data content of the
configuration word.
Input Image - Data Words and Status Words
The 8-word RTD module input image (defined as the input from the RTD
module to the CPU) represents data words and status words.
Input words 0 through 7 (data words) hold the input data that represent the
temperature value of the RTD input or ohmic value of the resistance inputs for
channels 0 through 7. This data word is valid only when the channel is enabled
and there are no channel errors.
When operating in Class 3 mode, input words 8 through 15 (status words)
contain the status of channels 0 through 7 respectively. The status bits for a
particular channel reflect the configuration settings that you have entered into
the output image configuration word for that channel and provide information
about the channel’s operational state. To receive valid status information, the
channel must be enabled and the channel must have processed any
configuration changes that may have been made to the configuration word.
O : 4 . 2
File Type
Element
Delimiter
Slot
Word
Delimiter
Word