Rockwell Automation 1771-PD PID MODULE (+DU) - Manual (Page 88)

Programming
Chapter 3
3Ć45
The loss tieback input will cause the corresponding loop output to be
held at its last value until the input is restored.
If either decoupling or cascading is selected and the tieback input to
loop 1 is lost, the output for both loops will be held regardless of the
status of the loop 2 inputs.
When the tieback input is used as a hardware analog input, loss of
input detection does not require the use of an external resistor.
The loss of a tieback input is indicated by bit B06 or loop status word
W61(W68) and bit B02 of the status monitor byte.
W61(W68)B05 Manual Mode. Reset to 0 indicates that the PID
module is controlling the analog output signal to the actuator. Set to
1 indicates that the module has relinquished control to the user
supplied auto/manual station, placing the station in the manual mode.
Manual operation could have been initiated at the auto/manual
station by the loss of analog power, or by setting W01 B00 to 1.
W61(W68)B04 Power-Up Complete. Rest to 0 at power-up. After
a valid power-up load/enter sequence initializes the module, this bit
is set to 1. (W68 B04 for loop 2 will be reset.) Refer to section titled
Load/Enter Sequence for additional information.
W61(W68)B03 Proportional Term>4095. Reset to 0 indicates that
the proportional term V
P
for the loop is less than or equal to 4095
(full scale). Set to 1 indicates that V
P
is greater than 4095.
W61(W68)B02 Derivative Term>VD MAX. Reset to 0 indicates
that the derivative term VD for the loop is less than V
D
MAX. Set to
1 indicates that V
D
is greater than V
D
MAX IN W27(W47).
W61(W68)B01 ALGORITHM OUTPUT<Minimum Output.
Reset to 0 indicates that the analog output is in range and greater than
or equal to the minimum output value VMIN in word W28(W48).
Set to 1 indicates that the analog output computed by the PID module
is less than the VMIN. The bit status is reported whether or not
output limiting has been selected. This status bit does not monitor a
SET OUT value downloaded from the PC processor into word
W05(W12).