Spectrum 1746sc-CTR4, Owner'S Manual, Page: 61 / 66

Appendix A: Floating Point Rate Mode
61
Setting the Rate Limit / R
Factor:
The R Factor function is used to activate the floating point mode. Setting
the value to -1 activates this mode. Use Bit 15 in your channel
configuration word to save the R factor in the modules non-volatile
memory.
Figure A.3 - Rate Limit / R Factor Word
15
0
Address
Rate Limit / R Factor O:e.z
9
8
Input Registers:
Channel Data
Counter Register, Low word:
This input data register contains the lower word of the counter
accumulator. This register is a signed 16 bit word in binary 2’s
complement format and will allow count values up to ±32K. This word is
used in conjunction with the counter’s upper output word when in the
extended count mode. Bit 15 represents the sign for each word.
Note: Extended count mode is not a valid configuration when using the
floating point rate mode.
Figure 4.10 -Counter Low Word
8 9
Counter Input Low
I:e.1
Rate Register words:
These two input data registers contain the rate value while operating in
floating point rate mode. The registers represent a 32 bit word in binary
2’s complement format and when combined form the 32 bit floating point
rate value.
Figure 4.12 -Counter Rate Word
8 9
I:e.x
I:e.y
Rate Input Low
Rate Input High
Data Words for Floating Point Rate Mode
!