Auto / manual operation (16a3 only) – Dwyer 16A User Manual

Page 15

tion.

See

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main-

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nt in

dis-

play,

ress

Page 15

AUTO / MANUAL OPERATION (16A3 ONLY)

The AUTO / MANUAL function allows you to manually adjust the output of the con-
trol. This is normally used during process setup or start up. It can also be used for
troubleshooting. To switch from AUTO to MANUAL press the AUTO / MANU-
AL key and hold for three seconds. The MANual indicator will light and the lower dis-
play will change from normal to showing the actual output in percent. The value will
be the actual percentage of output that was active when the key was pressed. This
is usually known as “bumpless transfer”.

If you wish to change the output while in manual, press the UP ARROW or
DOWN ARROW keys to change the value, and press ENTER to retain it. It is
important to remember that the value of the display can be read as 0 to 100% of the
full control output, or 0 to 100% of the range between

S10L

and

S10H

S20L

and

S20H

. If

APCt

is set for

rEAL

, a reading of 50% in MANUAL represents 10 mA

(Assuming a current output regardless of the

S10L

and

S10H

settings.) If

APCt

is set

for

AdJ

, then 50% in MANUAL will represent the mid point in output between

S10L

and

S10H

. (Assuming a current output, 4 to 20 mA, with

S10L

set to

and

S10H

set to

100

, 50% will represent 12 mA.)

To return to AUTOmatic control, press the AUTO / MANUAL key again. The
MANual indicator will go out, and the set point will take over. However, if you want
bumpless transfer back to AUTO, slowly change the percentage of output until the
process variable matches (or at least is close) to the set point. The further away the
PV is from the set point, the greater the “bump” or upset there will be in the out put.

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