Overloads

Some Gamry data files have a column in the data table with the heading Over and units of “bits”. This column consists of a string of 13 characters. If no overloads are detected during the acquisition of a data point, all of these characters are a period (“.”). A character other than “.” indicates an unusual and possibly serious overload condition existed during that data point. An example is shown below. As with all tables, the columns are <tab> delimited.

OCVCURVE TABLE 40
Pt T Vf Vm Ach Over
# s V vs. Ref. V V bits
0 0.258 -4.70E-001 0.00E+000 1.84E-003 ……….
1 0.516 -3.73E-001 0.00E+000 2.86E-003 techihssivarq

In this example, no overloads were detected for point #0, and each of the 13 characters is the “.” character. In point #1, all of the possible overloads are set. The non-period character in each position indicates that an overload was detected and recorded. The position of the character in the string indicates the type of overload. Thus, in point 1, a variety of overload conditions were detected. Their meanings are in the table below:

The position of the character in the string indicates the type of overload, not the character. An “h” in the 4th position and an “h” in 6th position indicate different kinds of overload conditions!

Pos. Char. Meaning Possible cause/remedy
1 t Timing problem Data rate is too fast
2 e Potential overload (electrometer hardware limit exceeded) Cell voltage is too big to measure
3 c CA Overload (Control Amplifier hardware limit exceeded) Potentiostat is oscillating or potentiostat cannot control the cell potential or current
4 h CA Overload sometime during the data point (History CA Overload) Transient overload, CA speed not optimized
5 i I Overload (I/E converter hardware limit exceeded) Wrong I/E range
6 h I Overload sometime during the data point (History I Overload) Current spike or transient
7 s Settling problem, hardware. Some hardware relay or range had not settled to its final position when the data point was taken. Experiment is too fast to autorange I/E at these current levels
8 s Settling problem, software. Either the operator or the Explain script triggered a data point before the hardware was in a stable state. Revise script or retrain operator
9 i ADC input was out of range for a current measurement Wrong I channel range or offset
10 v ADC input was out of range for a voltage measurement Wrong V channel range or offset
11 a ADC input was out of range for a measurement of the auxiliary ADC input Wrong Aux channel range or offset
12 r Raw data overrun. Raw data queue is filled. Host computer is too busy or too slow for this experiment
13 q Processed data overrun. Processing queue is filled. Host computer is too busy or too slow for this experiment