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My PC4/PC3/FAS1 Collects No Data

"My Experiment starts, but hangs up with 'Running...' or 'Autoranging' in the status bar and NO data."

Possible Causes:

1.  Interrupt (IRQ) Conflict

An interrupt is a signal generated by a hardware device such as a Gamry Potentiostat which tells the computer that the device requires attention. Gamry Potentisotats generate interrupts whenever a data point has been acquired. The software will wait patiently until that interrupt occurs. While it waits, the “Running…” or “Autoranging…” is displayed.

If another device in the computer is also trying to use the same interrupt request line (IRQ) confusion can follow. You can manually change the IRQ setting in the Gamry IRQ Manager entry under the Windows Device Manager. Fortunately, no switches are involved.

On motherboards with both ISA and PCI slots there can also be confusion if an ISA board (such as your Gamry Potentiostat) and a PCI board try to use the same IRQ. The IRQ needed by the Potentiostat can be reserved for ISA use –only– through the BIOS settings of the computer. These are generally access by pressing F2 or the Delete key when the computer first boots. Consult your motherboard’s manual for details on adjusting the settings on IRQs 5, 10, or 11 to work with “Legacy ISA”.

2.  Missing -5V Power Supply on Motherboard

At some point computer manufacturers eliminated the seldom-used -5V power supply that is required by the ATX specification.  Unfortunately, early Gamry PC4 potentiostat require it, and the no data acquisition can occur without it.  You can verify if your computer is missing the -5V supply by looking at the 20 pin ATX power supply connector on your motherboard:

5V to your potentiostat


If pin 18 is missing, your computer is not supplying the -5V to your potentiostat.  You can also check for the -5V supply by measuring voltage between pin 1 and pin 5 of the ISA slot.  If you cannot find a computer with this supply, Gamry can perform a modification to your potentiostat that will allow it to circumvent the missing -5V supply.