In past issues of The Optional Stop Newsletter, we've discussed several times when you might want to check the current setting of a given parameter to determine whether the machine is functioning as it should. We've also discussed times when parameters must be changed. While we've discussed the specific parameters (and sometimes even the specific parameter numbers) in detail, we've never actually told you how to change parameters.
Write down the current and new value
Our first suggestion is extremely important. You'll want to have the ability to reset the parameter to its original value. You might need to do so if you make a mistake when typing the new parameter value - or if your change didn't have the desired effect. This is especially important with eight-bit binary parameters, which have a series of ones and zeros. An example:
This might the value of parameter number 202. You might only have to change bit number two (the third bit from the right), meaning the new value will be 10011000. Again, it will be difficult to remember how to set this parameter back to its original value if you haven't written it down.
The parameter-write-enable (pwe) switch
This switch allows you to enter the parameter setting mode. With older controls like the 3, 5, and 6 series Fanuc controls (6MB for example), it is a physical switch. You must open the Fanuc control door and find the switch. It is a toggle switch, and is commonly placed at the lower left corner of the main (largest) circuit board. There may be several similar switches, so be sure to find the one labeled PWE.
Newer controls, including all current models, don't use a physical switch. Instead, they use a software switch. You'll find this switch on the SETTING page. With smaller display screens (9 inch, for example), you may have to use the page down button to find the item named PWE (again, PWE stands for parameter write enable). A setting of zero (0) stands for off. A setting of one (1) stands for on. When you first see the PWE setting, its value will be zero.
Turning on the switch
If you have a physical PWE switch, of course, you simply flip it to turn it on. If you have a software switch, you must set the PWE item to one (1).
When you set the PWE item to one (you must be in the MDI mode), the machine will go into alarm state and show alarm number 101. It is trying to tell you that you'll only be able to change parameters until you turn off the PWE switch. Simply ignore the alarm and press the key that brings you to the parameter page. While the word ALARM will still be flashing on display, you'll be able to change parameter settings.
Turning off the switch
When you're finished, you must turn off the PWE switch. If you have a physical PWE switch, of course, you simply flip it to turn it off. If you have a software switch, you must set the PWE item to zero (0). You must also press the RESET button to clear the alarm.