Lumel N31U User manual

N31U Service manual 1
DIGITAL PANEL METER

SERVICE MANUAL

N31U Service manual 2
Contents
1 Application......................................................................................................................................3
2 Meter set..........................................................................................................................................4
3 Basic requirements, operational safety............................................................................................5
4 Installation.......................................................................................................................................5
4.1 Installation method..................................................................................................................5
4.2 E ternal connection diagram...................................................................................................6
4.3 E amples of connecting the e ternal transducers....................................................................9
5 Service.............................................................................................................................................9
5.1 Description of the frontal plate................................................................................................9
5.2 Buttons' functions...................................................................................................................11
5.3 Programming meter parameters.............................................................................................12
5.3.1 How to change quantity of a selected parameter...........................................................14
5.3.2 Programmable meter parameters, default parameters....................................................15
5.4 Meter functions......................................................................................................................19
5.4.1 Measurement..................................................................................................................19
5.4.1.1 Averaging the measuring quantity..........................................................................20
5.4.1.2 Minimum and ma imum measuring values...........................................................20
5.4.1.3 Mathematical functions..........................................................................................21
5.4.1.4 Individual characteristic.........................................................................................21
5.4.2 Alarm output..................................................................................................................23
5.5 RS-485 interface....................................................................................................................24
5.5.1 Connection.....................................................................................................................24
5.5.2 Description of the MODBUS protocol implementation................................................25
5.5.3 Implemented functions of MODBUS protocol..............................................................25
5.5.4 Map of the registers........................................................................................................26
5.5.4.1 Registers 4000 – 4024............................................................................................26
5.5.4.2 Registers 4200 – 4219............................................................................................29
5.5.4.3 Registers 7500 – 7530 and 7000 – 7030................................................................30
5.5.4.4 Registers 7600 – 7668 and 7200 – 7336................................................................31
6 Error codes.....................................................................................................................................33
7 Technical data................................................................................................................................34
8 Ordering code................................................................................................................................36

N31U Service manual 3
1 Application
The N31U meter is a digital panel meter adapted to be fixed to the panel designed to
measure standard analog signals used in automation. N31U meters enable the
measurement of standardized voltage and current signals, the signals from RTD and
thermocouple sensors. The measuring value can be freel converted into the required
value using the mathematical functions or an individual characteristic.
Additionall , the meter supports the programmable alarm with the dela activation and
deactivation function as well as a memor of the alarm event. The functionalit of the
meter is complemented b RS-485 interface.
The user interface consists four buttons and the high contrast LCD displa with back-light.
Thanks to the two-line displa , it is possible to set the selected unit, displa simultaneousl
the measuring value and the value not converted b individual characteristics, as well as a
clear and user friendl menu with simultaneousl visible the parameter name and its value.
Features of the N31 meter:
•Universal measuring input including the standard signals used in automation.
•Measuring sensor failure indication.
•High contrast LCD displa with built-in backlight.
•Two-line displa .
•Programmable unit of measuring value.
•Possibilit to simultaneousl displa a measuring value and not converted quantit .
•Programmable displa ed precision with automatic setting of a decimal point.
•Possibilit to program the measuring range (narrowing).
•Additional measurement of minimum and maximum values during the moving
window, with the possibilit of programming one of these values to be displa ed as
the basic one.
•Programmable alarm with the functions of programmable dela s of alarm activation
and deactivation, triggered b a specific controlling value.
•Possibilit to control the alarm output (rela ) via the RS-485 interface.
•Built-in b default RS-485 interface with MODBUS RTU protocol support.
•Possibilit to password protect the settings against unauthorized modification.
•Monitoring of set parameters.
•Measuring quantit conversion using the mathematical functions.
•Measuring quantit conversion using the 32 points individual characteristic.

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•Programmed averaging time - averaging algorithm in a specified time using
standard averaging (determining the number of measurements to be averaged) and
averaging based on the moving window algorithm with a given averaging time.
•Signaling of alarm operation b highlighting the LED of the active alarm.
•Registration of minimum and maximum measuring value.
•Galvanic separation of the connections: alarm output, measurement outputs,
auxiliar suppl outputs, RS-485 interface and suppl ing input. (Note: Measurement
inputs and auxiliar suppl are at one potential).
•Protection degree from the front IP65.
•Meter overall dimensions 96 x 48 x 100 (with the terminals).
•The casing is made of a self-extinguishing plastics.
•Wide range of suppl voltages.
The view of the N31U meter is shown in Fig. 1.
2 Meter set
The meter set includes:
•Meter N31U – 1 pc
•Clamps to fix in the panel – 4 pcs
•Seal – 1 pc
Fig. 1: View of the N31U meter.

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3 Basic requirements, operational safety
In terms of a user safet , the N31U meter meets the requirements of the EN61010-1
standard for the devices intended for use in facilities compliant with the third categor of
installations.
Comments concerning safety
•Assembl and installation of the electrical connections should conducted onl b a
person authorised and certificated to perform assembl of electric devices.
•Alwa s check the connections before turning the meter on.
•The meter is designed to installation and usage in the industrial electromagnetic
environment.
•A switch or a circuit-breaker should be installed in the building or facilit . It should
be located near the device, easil accessible b the operator, and suitabl marked.
•Removal of the meter electronics during the warrant period voids the warrant .
4 Installation
4.1 Installation method
The N31U meters are designed to be mounted in a panel. Prior to installation a 92 +0.6 x
45+0.6 mm slot must be made in the panel. The maximum thickness of the panel material
cannot exceed 6 mm. The meter should be mounted from the front of the panel with
disconnected meter connection strips.
Before inserting the meter into the panel check the correct position of the meter seal and
make sure that the edges of the panel are not sharp what could damage the seal. After
inserting the meter into the slot, mount it with the mounting brackets provided in the meter
set (Fig. 2).
Fig. 2: Meter fixing.

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Electrical connections of the meter should be made with the wires with the cross-section
up to 2.5 mm2. Detachable sockets with the plugs of 5.08 mm pitch can be used for the
connections.
The external dimensions of the meter are shown in Fig. 3.
4.2 E ternal connection diagram
The meter's electrical connections must be made with wires whose cross-section does not
exceed 1.5 mm2 for terminals numbered 1 to 10 (lead-in grid of 3.81 mm) and 2.5 mm2 for
terminals numbered 11 to 18 (lead-in grid of 5.08 mm).
The view of the meter from the connectors' side is shown in Fig. 5. The upper terminal strip
is optional and depends on the accessories of the meter.
The circuits of successive groups of the terminals are separated from each other, as
shown in Fig. 4.
Fig. 3: Meter overall dimensions.
Fig. : Galvanic isolation of the N31U meter.
Suppl
Measuring inputs, output 10/24 V d.c.

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Note: Unused terminals of the terminal strips must not be connected to any signals.
Detailed description of the signals is shown in the table below, and the connection of the
measuring signals is shown in Fig. 6.
Terminal Function Description
1, 2, 3, 4,
5, 7, 8
Measuring inputs Measuring inputs for connecting sensors, transducers or
output signals from the other devices. Examples of the
connections are shown in Fig. 6.
6, 9 Suppl output Auxiliar suppl ing output (24 V) for suppl ing the
potentiometers, transducers, e.g. head-mount transducers
supplied b a current loop. Maximum current carr ing
capacit of the output is 30 mA.
11, 12, 13 RS-485 RS-485 interface signals
Fig. 5: Signals on the terminal strips.

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14, 15 Alarm Alarm output, which is NO rela contact.
16, 17, 18 Power suppl Meter power suppl connection. Depending on the power
suppl voltage range, use connectors 17-18 or 16-17.
Note: Connecting the power supply to connectors
16-18 will damage the meter!
The connection of the basic measured signals is shown below. The inputs not used in the
configuration should be left unconnected.

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4.3 E amples of connecting the e ternal transducers
Connections of the head-mount transducers when the transducers are supplied directl
from the N31U meter are shown below. In the case of the transducers with a voltage
output, the maximum current carr ing capacit of the auxiliar suppl output is 30 mA and
the auxiliar suppl source is onl active for selected input ranges of 10V, 20MA and
Pot10V.
5 Service
The N31U meter user interface includes an LCD displa and the buttons which enable to
displa the measuring value, a full configuration and setting of the meter or modification of
the parameters.
After turning the meter on the displa shows the name of the meter and the software
version. If there is no error during meter initialization process, the meter will switch to
displa ing the measuring value. If during the initialization an irregularities or deviations
are detected, than a message with information about a detected error will be displa ed
(see point 6 - Error codes).
5.1 Description of the frontal plate
View of the front panel of the meter is shown in Fig. 6. The LCD displa with backlight and
4 buttons are on the front panel. The description of the displa fields is shown below. The
button functions are shown in the section 5.2.

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Designation Description
L1 The upper (main) line of the displa has 6 characters used to displa a
measuring value or a parameter value during the meter configuration.
L2 The lower (auxiliar ) line of the displa has 5 characters used to displa a
measuring value, not converted b the individual characteristic or,
according to configuration, a unit or current time.
Z1 Measuring value averaging indicator. Illuminated averaging indicator
informs that the set measuring value averaging period has not elapsed et.
ALI Alarm status field. This field contains the indicator informing about the
alarm status. Illuminated alarm indicator means that an alarm event is in
progress and the rela corresponding to the alarm is activated. Flashing
s mbol means that the alarm state is saved (if the alarm memor is
activated).
B1...B4 Meter operation buttons. The description of the button functions and their
various combinations are shown in section 5.2.
VO Indicator informing that the auxiliar suppl output voltage is stable - the
output voltage value is stable and within the specified range (see technical
data).
The lower line of the displa can be configured to displa the unit. The available units with
the corresponding value in the register 4008 of the MODBUS protocol are shown below.
Value in the
register 4008
(setting)
Unit
Value in the
register 4008
(setting)
Unit
Value in the
register 4007
(setting)
Unit
0 ----- 20 kvarh 40 h
1 mV 21 Mvarh 41 m3
2 V 22 VAh 42 obr
3 kV 23 kVAh 43 pcs
4 mA 24 MVAh 44 imp
Fig. 6: Front panel of the meter.