Watlow F4T

Watlow F4T • 154 • Chapter 5 Function Reference
Signals
Direction
Label Type Function
Receivers
IN Digital The signal that sets the output
Hold Digital The signal that holds the output
Transmitter - - - - Digital
Follows the input (IN) when HOLD is false. Latches at the
value of the input (IN) when HOLD becomes true.
Function
To have an output that follows the input when another input is false and holds the last value
when the latching input becomes true, set Function to Latch.
Error Handling
Use Error Handling to select the output's value and error status when the function cannot de-
finitively determine the result.
Options:
• True Good: output's value is true (on) with no error
• True Bad: output's value is true (on) and has an error
• False Good: output's value is false (off) with no error
• False Bad: output's value is false (off) and has an error
RS Flip Flop
True (on, 100%) at the Set input sets the output to true (on, 100%) unless the reset (Rst) input
is true (on, 100%). Whenever Rst is true (on, 100%) the output is false (off, 0%).
To understand the RS Flip Flop’s behavior consider these scenarios illustrated in the timing
diagram below:
1. Set turns the output on, Rst turns it off.
2. If Rst is true when Set becomes true, the output remains off until Rst becomes false.
3. Set has no effect when the output is already on.
Signals
Direction
Label Type Function
Receivers
Set Digital Sets the output to true
Rst Digital
Sets the output to false, takes precedence over the Set
input
Transmitter
- - - - Digital
True after being set by the Set input and false after being
reset by Rst