Controlling and Timing

Controlling the Module

Hardware inputs from the field can be used to:

Increment/decrement the input counters with serial pulses from encoders or other square wave sources.
Set direction of count.
Reset the outputs.

Hardware inputs from the field and software commands are used together to:

Hardware inputs from the field or software commands can be used to:

Software commands can be used to:

Configure the counters for pulse (tachometer) or quadrature mode.
Configure for 16 or 32 bit counters, with or without output assertion.
Configure the module to operate in either count or rate-sample mode.
Option for outputs to operate or not operate if backplane bus communication is lost (i.e., a fault condition).
Option for outputs to switch on when setpoint and/or maximum values are reached.
Define the setpoint and maximum count values.
Define ON time for outputs.
Disable outputs.
Read the input counter totalizing or rate sample values.
Retrieve the old (previous) input counter value after the counter has been preset.

Timing Diagrams

The following figure shows the EHC20200 timing diagrams.

Timing Parameter Table

The following table shows the EHC20200 timing parameters.

Timing Parameters		Limits
	Filter 200 Hz	Filter 200 Hz	No Filter 500 khz
Tdly1	Count to Output Assertion Delay (MAX)	4.8 ms	40 μs
Tdly2	Preset/Reset to Output Delay (MAX)	4.8 ms	40 μs
Tpw1	Count/Reset Pulse Width (MIN)	2.5 ms	1 μs
Tpw2	Preset Pulse Width (MIN)	2.5 ms	500 μs
Tst	Enable/Reset/Preset to Count Setup Time (MIN)	2.5 ms	2 μs
Thold	Enable/Reset to Count Hold Time (MIN)	2.5 ms	2 μs

NOTE: The timing parameter limits are measures at the module field terminal connector at the logic low threshold level.