11
Schematic diagram
PREMASGARD
®
121x - Modbus
G
PREMASGARD
®
121x - Modbus
| Zero point calibration and configuration
After successful zero point calibration,
the output voltage is 5 V at 0 Pa pressure difference
(with the offset knob in central position)!
Output voltage 0 ...10 V
for pressure difference - ∆P ... +∆P
1 2 3 4 5
12345678
ON
DIPA
123456
ON DIPB
Plug for
display
offset
auto
zero
min. max.
–UB GND
Shielding
RS485 Modbus A RS485 Modbus B
+UB 24V A
C/DC
mode
Plug for display
contact is
on the right side
Offset correction
pressure
ca. ±10% of final value
LED and
pushbutton
zero point setting
(auto zero)
DIP A: Bus address
DIP B: Bus parameters
(Baud rate, parity ...)
Telegram indicator
Reception (LED green)
Error (LED red)
1 2 3 4 5
12345678
ON
DIPA
123456
ON DIPB
Plug for
display
offset
auto
zero
min. max.
–UB GND
Shielding
RS485 Modbus A RS485 Modbus B
+UB 24V A
C/DC
mode
Plug for display
contact is
on the right side
Offset correction
pressure
ca. ±10% of final value
LED and
pushbutton
zero point setting
(auto zero)
DIP A: Bus address
DIP B: Bus parameters
(Baud rate, parity ...)
Telegram indicator
Reception (LED green)
Error (LED red)
Offset adjustment is done at a potentiometer on the circuit board within
an adjustment range of ± 10 % of the device’s pressure range.
Ex-factory this potentiometer is in center position and is lacquer sealed.
All settings and adjustments that are made before must be done in this
configuration.
Offset adjustment is carried out using a tool called “screwdriver 2.5”
(blade with in mm).
Automatic offset setting
1.
Before setting the zero point, the device must be in operation
for at least 60 minutes.
2.
Connect pressure inputs P (+) and P (–) by means of a hose
(pressure difference between both inputs = 0 Pa).
3.
For zero point setting press button uninterruptedly for 5 seconds.
A LED signalises prompting the calibration by short flashing,
and after a short countdown the measured (current) offset value
is added to the measurand and zero voltage safe stored.
Correct calibration is confirmed by steady light of the LED
for 3 seconds respectively indicated in the display (optional)
by switching from “AUTO 0” to “PROG 0”.
Note: By releasing the button during the countdown (counter > 0),
zero point setting is immediately terminated!
Manual offset adjustment
At the potentiometer OFFSET ∆P can be balanced.
The adjustment range is ca. ± 10 % of the pressure range.
Here another reference point different from zero point can be used.
Display - individually
programmable
