#QNAN on all wired analog inputs - old forum post



Joined on 02-08-2008
Posts 3
1.#QNAN on all wired analog inputs

I’m configuring a PAC system with 6 analog +/-20mA input modules (SNAP-AIMA-4).

Using PAC Manager, I can see the currents on all the wired inputs. All the inputs are sourced by 4-20mA transducers and most are currently wired in. All of the currents displayed in PAC Manager appear to be correct (minus a few minor calibration issues (ie. 3.6mA instead of 4mA when off).

The problem is that PAC Control Basic is showing a 1.#QNAN in the IVAL column for all of the wired inputs (inputs that haven’t been wired yet are showing 0 and seem to be ok). I’ve changed the scaling on each of the inputs from 4-20mA to 0-20mA just in case there was an issue with the input being below 4mA, but nothing’s changed.

In my strategy, I’m moving the inputs to float variables in one block and applying the variables to simple equations (add/sub, etc) in the next block. The calculation block is constantly throwing ‘Overflow errors’ for each line because of the QNAN status (I’m assuming).

How can I resolve a QNAN on the IVAL of a SNAP-AIMA-4 input in Opto Control?
04-08-2008, 1:50 PM

Joined on 02-08-2008
Posts 3
Re: 1.#QNAN on all wired analog inputs

Looking through the PAC Control Manual, I found the problem.

The system consists of a single PAC on a rack with 6 AIMA-4 modules. In the I/O Unit configuration (in PAC Control), I set the IP Address of I/O Unit (the PAC) to its actual LAN address, not its loopback address (

Changing the IP in the I/O Unit config to solved the problem.