GFK-0825F Chapter 7 Monitoring and Controlling Field Control Data 7-5
7
Forcing/Unforcing the Displayed Reference
Individual I/O points can be forced and unforced from the Hand-held Monitor (the HHM's circuit
forcing capability must be enabled to use this function).
Forcing an I/O point changes its state in the Bus Interface Unit's EEPROM memory. If the circuit
is an output, the physical state of the output also changes. If the circuit is an input, the forced input
data is sent to the CPU. Once forced, a circuit retains the forced state or value if power is removed.
The forced circuit ignores data from an attached input device, or output data from the CPU. The
force can ONLY be removed from th e Hand-held Monitor.
1. Select the correct data type for forcing (Binary for discrete I/O or Decimal for analog I/O).
Press F4. to change the data type.
I00001 *0 B
< > frc hex
2. Press the F3 (force) key to for ce the reference now being di s p la yed:
frc unfrc
I00001 1 B
frc unfrc
I00001 *0 B
Current state or value
Indicates force is in effect
3. Press F3 (force) again. Then, use the HHM keypad to enter the force state or value.
4. Use the F4 (unforce) key from th e same screen when you want to unfor ce the point.