Chapter 2 Operating Your Frequency Counter
Using the LIMITS Menu Keys
2-38 Operating Guide
2
Limits Testing Example 5—Sending the Limit-Detect Output to the RS-232
Serial Port
NOTE If you cycle power, you will lose everything except saved measurement setups and
special parameters saved to non-volatile memory; therefore, make sure you use the
Save and Recall functions of the Counter to retain the measurement setup prior to
powering down to set up the Limit-Detect Output line (pin 4) of the RS-232 serial
connector. Refer to the appropriate section in this chapter for details on how to use
Save and Recall.
1 To use the Limit-detect output from the serial port, perform the following steps:
a. Save your measurement setup that includes your Limit Testing choices, by
simply pressing the Save & Print key until SAVE: 1 is displayed, then Enter
key to save to register 1.
b. Turn off the Counter.
c. Press and hold Recall (Utility) key, then press POWER key.
d. Press Recall (Utility) key until DTR: is displayed.
e. Press any one of the arrow keys until DTR: LIMIT is displayed.
2 Press Run key.
3 Press Recall (Utility) key until RECALL 1 is displayed, then wait a few seconds
to recall the measurement setup saved in register 1.
Since your measurement setup included your settings for upper and lower limits, and
LIM TEST: was set to ON, the Counter is now set for limit testing with the Limit-
detect output.
If a measurement drifts out of the user-entered limits, the Limit annunciator in the
display will light. Also, pin 4 on the RS 232 connector will change state (to a low-
voltage RS-232 level) to flag each time a measurement drifts out of the limits. (RS-
232 voltage levels swing from ±12V.)
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