Frequency Counter Cylinders (RPM)

Controls: Options >> Frequency Counter >> Cyl
Macro : FcountCyl

The Cylinders (Cyl) control is at the far right end of the Frequency Counter window. It works in conjunction with RPM mode, and should be set to twice the number of trigger events per revolution. The default value is 2, for one event per revolution.

If you are using the RPM mode as a tachometer to measure engine RPM based upon spark or fuel injection pulses from a single cylinder on a 4-stroke engine, set this control to 1. (Set it to 2 for a 2-stroke engine.)

If you are monitoring all spark or fuel pulses on a 4-stroke engine, set this control to the actual number of cylinders. For example, use this when monitoring the coil wire or breaker points on a conventional distributor engine. For a 2-stroke engine, set it to twice the number of cylinders.

If you are monitoring pulses from the crankshaft position sensor, set Cylinders to twice the number of actual teeth present on the gear... do not count any missing teeth used to provide a reference. (They don't produce trigger pulses, so the Frequency Counter won't count them either.)

However, if you are monitoring a simulated sensor that allows you to trigger on just the first pulse of each revolution, set Cylinders to 2 for one event per revolution. If you set the Trigger Level to trigger on every pulse, as you would with a real engine sensor, then use twice the actual teeth.

For all other motors and rotating machinery, set Cylinders to twice the number of pulses per revolution, which may be quite large if you are sensing teeth on a large gear. The Cylinders control accepts values up to 2000, which will support a 1000-tooth gear.

See the Engine RPM Measurement topic under Automotive Applications in the Applications section. It contains information about Trigger settings, input voltage limiters to prevent damage to your sound card, and tips on how to obtain trigger signals from spark plug wires or fuel injectors without direct electrical contact.

See also Frequency Counter