421QIM - Quad Input Module


The 421QIM is a 4 channel digital input module. The module has 4 digital inputs with weak pull-up resistors, suitable for use with potential-free switched contacts.


Frequently asked questions

When I have a QIM in my design, some other modules will not stream correctly. Why does this happen?

Version 2.01 of the QIM firmware can prevent other modules on the bus from operating correctly in streaming mode. For example a, VEI may work perfectly when using the module test program, but fail to send any data when streaming. Upgrading the QIM to firmware V2.02 or above should resolve this issue.

Which Colour wires are which channels?

  • Blue = Channel 1 (IN1)
  • Green = Channel 2 (IN2)
  • Yellow = Channel 3 (IN3)
  • Red = Channel 4 (IN4)

When my sender closes, the LED on the channel illuminates, but the E-Plex output doesn't change state. What's wrong?

The LED is connected in series with the input contacts. This means that if there is too much resistance across the sender contacts, the LED will illuminate, but the module will not be able to detect the voltage drop.

I need to sense an input that has a higher resistance than dry contacts- is this possible?

v2.03 of the 421QIM firmware and above include adjustable analog thresholds for each channel. This allows the inputs to be adjusted so that they can detect higher input resistances. Each channel is connected to an internal voltage source through a pullup resistor. This means that with the inputs disconnected, you will see 5 or 6 Volts on the input wires. As you connect the input to ground, the voltage gets pulled down and the module detects it as an input. If you right click a 421QIM in Elogic, and select unique properties, a window will open that allows you set the thresholds. When digital mode is ticked (as default) it will behave like a v2.02 QIM. When unticked, the thresholds can be changed manually. An input must be pulled below the low threshold to register as on, or true. An input needs to be above the high threshold to register as off, or false. The gap between the two thresholds can be used to allow for fluctuations in voltage or resistance and prevent false triggering.

It is easiest to set the threshold levels through the module test program, with a module phyiscally connected. You can then see the input voltage in real time, and adjust the thresholds as required. Changes made in the test program will update the unique properties in the schematic, and programming another module will automatically set it to the thresholds you have created. If you do not see the threshold dialogue in the unique properties for the 421QIM you will need to update Elogic to the latest version. Also note the point above- the LED may not bear much resemblance to the input state, particularly if you set a high input threshold.

hardwarepub/modules/421qim.txt · Last modified: 2016/02/22 11:26 by Bob Lynas
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