UMAX140610. LIN
– J1939 CAN Protocol Converter with PWM Output. Version 1
Page: 33-81
3.4.5 X-Axis, Time Response
As mentioned in Section 3.4, a Lookup Table can also be used to get a custom output
response where the “
X-Axis Type
” is a
‘Time Response.’
When this is selected, the X-Axis
now represents time, in units of milliseconds, while the Y-Axis still represents the output of the
function block.
In this case, the
“X-Axis Source”
is treated as a digital input. If the signal is actually an analog
input, it is interpreted like a digital input per Figure 4. When the control input is ON, the output
will be changed over a period of time based on the profile in the Lookup Table. Once the
profile has finished (i.e. index 10, or
‘Ignored’
response), the output will remain at the last
output at the end of the profile until the control input turns OFF.
When the control input is OFF, the output is always at zero. When the input comes ON, the
profile ALWAYS starts at position (X
0
, Y
0
) which is 0 output for 0ms.
When using the Lookup Table to drive an output based on
time
, it is mandatory that setpoints
“Ramp Up (min to max)”
and
“Ramp Down (max to min)”
in the PWM Output function block
be set to
zero
. Otherwise, the output result will not match the profile as expected. Recall, also,
that the Y-Axis range of the table should be set to match the Analog Output 1 range in order to
get a 1:1 response of table output versus drive output.
