RM-8DI2 Usage Tips

Sourcing Inputs

This is the most common application. Use the –F field wired base for direct field wired inputs from devices that switch positive DC power into the inputs of this module. The -F base is pre-wired to provide DC power on even numbered screw terminals so that pairs of wires from each switch can be directly connected to the wiring base.

Sinking or Floating Inputs

Use the –U universal wiring base if your switches return to ground or if floating inputs are required to connect to isolated or undetermined inputs. Each pair of terminals, corresponding to an input channel, is fully isolated from all other channels and may be connected in any convenient manner. Each input is bipolar (accepts either positive or negative signals) and so the two terminals are interchangeable.

Slow / Fast Response

Select fast response for minimal input filtering to respond to DC input changes in 5 mS. Slow response looks for stable inputs for approximately 25 mS to filter contact bounce (important when counting mechanical switch closures) in noisy environments.

Pulse Counters

Enable pulse counters to increment an analog input register each time an OFF to ON transition occurs on the corresponding input. These counters are volatile (forget their counts if power is lost). These counters cannot be reset under software control. Typically, retention of the values and resetting the counts is accomplished in software in the host computer that polls these inputs.

High Speed Counter

The first channel (and only the first channel) may be configured as a high speed counter to record pules as fast as 2 KHz. In this high speed mode, the input filtering is not active, and even short input spikes will most likely be counted.