5-2
Using negative logic for programmable I/O terminals
The negative logic signaling system can be used for the digital input and output terminals by setting
the function code data specifying the properties for those terminals. Negative logic refers to the
inverted ON/OFF (logical value 1 (true)/0 (false)) state of input or output signal. An active-ON signal
(the function takes effect if the terminal is short-circuited.) in the normal logic system is functionally
equivalent to active-OFF signal (the function takes effect if the terminal is opened.) in the negative
logic system. An active-ON signal can be switched to active-OFF signal, and vice versa, with the
function code data setting.
To set the negative logic system for an I/O terminal, enter data of 1000s (by adding 1000 to the data
for the normal logic) in the corresponding function code. Some signals cannot switch to active-OFF
depending upon their assigned functions.
Example: "Coast to a stop" command BX assigned to any of digital input terminals [X1] to [X3] using
any of function codes E01 through E03
Function code data BX
7 Turning BX ON causes the motor to coast to a stop. (Active ON)
1007 Turning BX OFF causes the motor to coast to a stop. (Active OFF)
Restriction on data displayed on the LED monitor
Only four digits can be displayed on the 4-digit LED monitor. If you enter more than 4 digits of data
valid for a function code, any digits after the 4th digit of the set data will not be displayed, however
they will be processed correctly.
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