Appendix A Floating Point Rate Mode; Overview; Configuring Each Input Channel For Floating Point Rate - Spectrum Controls SLC 500 User Manual

Overview

Configuring Each
Input Channel for
Floating Point Rate
Input Registers – Channel Data
User's Manual Pub. 0300181-07 Rev. A
Appendix A
Floating Point Rate Mode
Read this appendix to:
Configure rate for floating point mode.
•
Read input words to get data.
•
Use ladder logic to create floating point value.
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The floating point rate mode allows the user to monitor rate to a higher degree of
accuracy. The default mode for the counter module provides 1Hz rate resolution.
The floating point mode allows the module to report rate resolution of up to
0.0001Hz. The rate resolution is dependent on the input signal speed. Low speed
signals will provide the highest resolution. As rate increases the frequency
accuracy will decrease.
The Data Register format for floating point is different that the default register
mode. The data words have been moved to accommodate the floating point rate
value. Your ladder logic must be modified to support this new word format. In
order to activate the floating point mode, you must set the Rate Factor to a value
of -1.
The following steps are necessary to accomplish this:
1. Load the value (-1) into the Rate Limit / R Factor
2. Toggle the Program Scale Factors configuration bit (Bit 15) to write the
configuration to the module.
3. Clear the Program Scale Factors configuration bit (Bit 15).
4. Clear Rate Limit / R Factor Value
5. Create ladder logic to join the two input works to create your floating
point value.
The channel data consists of 4 words, the lower counter data value, the rate data
high value, the rate data low value and the channel status data.