AIM Binary Tree
AIM2505A Technical Manual V2.03
30
Registers 89-92 - Frequency inputs, pulse width ratio
These give the measured pulse width ratio in tenths of a percent (0.1%) for the four
frequency inputs.
Method:
Ratio = 100.0% * (input high count) / (input high count + input low count)
Example: if a register has a value of 491, the pulse width ratio is 49.1%
When the module detects that the input state of a channel has not changed for a
while, the pulse width ratio value will be zeroed for that channel. The value is
updated again when enough new changes have been detected in that input.
There is some hysteresis in this monitoring and the actual time to change between
these states varies, but this should generally happen under a second.
Registers 97 - Frequency inputs, input state
These give the state of the input for each channel. This enables all four channels to
be used as digital input channels.
Registers 98 - Phase direction for frequency input 1 versus input 2
The frequency inputs 1 and 2 can be paired to measure phase direction between
pulses in these two inputs:
Base for the measurement is channel 1
If input 1 goes high before input 2, the value is zero
If input 2 goes high before input 1, the value is one
Combined with pulse count from either channel will enable measurement of position
with a suitable sensor. The sensor must supply two input pulse trains that are in
quadrature, i.e. always shifted by 90°C in relation to each other.
Note that if the two inputs see different frequencies, the information in this register is
meaningless.
Registers 99 - Phase direction for frequency input 3 versus input 4
See previous register for explanation, only the paired channels are different.
Register 200 - Bus address
The I/O bus node address of the module. The CIAO bus master software will write
the module node address into this register if the module is found on the I/O bus. If
the module is not found, this register will remain uninitialized.