IM 12D08N04-01E
5-24
5. Parameter Setting
5-3-5. Contact outputs
Code 40
*S1, *S2
Process relays can be set for a variety of alarm and control function.
41, 42
*S3 & *S4
and 43
Digit "X" sets the type of trigger:
Off means that the relay is not active
Low setpoint means that the relay is triggered by a decreasing measurement.
High setpoint means that the relay is triggered by an increasing
measurement."HOLD" active means that there is maintenance activity in
progress so the
measurement is not live.
For *S4 There is the extra possibility to set up for "FAIL" indication.
Digit "Y" sets the control action:-
Process alarm is a simple On/Off trip controlled by the high/low setpoint.
Proportional duty cycle control has a pulse width modulation for proportional
dosing with solenoid valves.
Proportional frequency control is used for controlling electrically positioned
valves.
Temperature alarm is an On/Off trip on the measured temperature.
Digit "Z" sets zero alway.
Service code 40-43 can be selected as USP contacts
All 4 contacts can be selected as USP alarms.
The contact closes when the USP setpoints are exceeded. In this way it is possible to adjust a
safety margin.
For example, if the temperature is 64
°
C and the setpoint (safety margin) is adjusted for 10%,
then the contact closes at 0.9* 2,2 = 1.98 microsiemens. Additionaly, when the water
conductivity exceeds the USP limit the display shows E13 and the FAIL mode is activated as
set in Service code 57.
Code 44
*D.TIME
The delay time sets the minimum relay switching time. This function can be
adjusted to give a good alarm function in a noisy process, preventing the relay
from "chattering" or repeatedly switching when the signal is close to the
setpoint. See fig 5-3.
*P.HYST
The hysteris is the value beyond the setpoint that the measured value must
exceed before the control function will start working. For conductivity this
setting is expressed in % of programmed setpoint value.
Code 45
*RANGE
Proportional range is the value above (or below) the setpoint that generates full
output in proportional control. This is expressed in % of the programmed output
span.
*PER.
The time period of the overall pulse control cycle (one ON and one OFF
period). See fig 5-4.
*FREQ.
The maximum frequency for the pulse frequency control. See fig 5-5.
Code 47
*EXPIR
When a system is set up to control on the relay outputs, the expiry time can be
enabled to warn of an ineffective control. In other words, when the setpoint is
exceeded for more than 15 minutes an error message is generated. This can
mean, for example, that the reagent tank is empty.
*tE.min
Set expiry time by minutes.