Helios PD2-6080/PD2-6081 Modbus
®
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Instruction Manual
51
Acknowledging Relays
There are three ways to acknowledge relays
programmed for manual reset:
1. Via the programmable front panel function keys
F1-F3 (Example: F3 assigned to ACK).
2. Remotely via a normally open pushbutton wired
to the F4 terminal.
3. Remotely via a normally open push button wired
to one of the digital inputs and the +5 V terminal
on the digital I/O connections.
When the ACK button or the assigned digital input is
closed, all relays programmed for manual reset are
acknowledged.
Acknowledging Relays with Remote
Control Station
Relays may be remotely acknowledged by connecting
the
to either the F4 terminal or a digital
input as described above.
Pump Alternation Control
Applications (
Altern
)
For pump control applications where two or more
similar pumps are used to control the level of a tank
or a well, it is desirable to have all the pumps operate
alternately. This prevents excessive wear and
overheating of one pump over the lack of use of the
other pumps.
Up to 4 relays can be set up to alternate every time
an on/off pump cycle is completed. The set points and
reset points can be programmed, so that the first
pump on is the first pump off.
Application #1: Pump Alternation
Using Relays 1 & 2
Set and Reset Point Programming
Relay
Set Point
Reset Point
Function
1
30.000
10.000
Controls
pump #1
2
35.000
5.000
Controls
pump #2
3
4.000
9.000
Controls
low alarm
4
40.000
29.000
Controls
high alarm
1. Relays 1 and 2 are set up for pump alternation.
2. Relays 3 and 4 are set up for low and high alarm
indication.
Pump Alternation Operation
1. Pump #1 turns on when the level reaches
30.000, when level drops below 10.000 pump #1
turns off.
2. The next time the level reaches 30.000, pump #2
turns on, when the level drops below 10.000,
pump #2 turns off.
3.
If the level doesn’t reach 35.000 pump #1 and
pump #2 will be operating alternately.
4. If pump #1 cannot keep the level below 35.000
pump #2 will turn on at 35.000, then as the level
drops to 10.000 pump #1 turns off, pump #2 is
still running and shuts off below 5.000.
5. Notice that with the set and reset points of pump
#2 outside the range of pump #1, the first pump
on is the first pump to go off. This is true for up to
4 alternating pumps, if setup accordingly.
6. Relay #3 will go into alarm if the level drops
below 4.000 and relay #4 will go into alarm if the
level exceeds 40.000.
MENU RIGHT UP ACK
ACK
MENU
PREV
F1
NEXT
F2
SCAN
F3
P-
F4
P+
COM
V+
3
4
1
2
5
mA+ COM
V+
mA+
7
8
6
9
O1 O2 O3 O4 G
I
1
I
2
I
3
I
4
+5
Ground
5 VDC
ACK
