
Transmitter M400 94
© 02 / 2010 Mettler-Toledo AG, CH-8606 Greifensee, Switzerland Transmitter M400
Printed in Switzerland 52 121 378
10.3 Mode
(PATH: MENU / PID Setup / Mode)
This menu contains the selection of control modes using relays or analog outputs.
Press [ENTER].
10.3.1 PID mode
This menu assigns a relay or analog output for PID control action as well as details of their op-
eration. Based on the control device being used, select one of the following three paragraphs for
use with solenoid valve, pulse input metering pump or analog control.
Pulse Length – If using a solenoid valve, select ”Relays” and ”PL”, pulse length.
Choose the first relay position as #3 (recommended) and / or the second relay position
as #4 (recom mended) as well as the pulse length (PL) according to the table below. A longer
pulse length will reduce wear on the solenoid valve. The % ”on” time in the cycle is proportional
to the control output.
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NOTE: All relays from #1 to #6 can be used for the controlling function.
1
st
Relay Position
(#3)
2
nd
Relay Position
(#4)
Pulse Length (PL)
Conductivity
Controlling
concentrating reagent
feed
Controlling dilution water
Short (PL) provides
more uniform feed.
Suggested start point
= 30 sec
pH / ORP Feeding base Feeding acid
Reagent addition cycle:
short PL provides more
uniform addition of
reagent. Suggested start
point = 10 sec
Dissolved
Oxygen
Reverse control action
Direct acting control
action
Feed cycle time: short
PL provides more
uniform feed. Suggested
start point = 30 sec
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