Nokeval 6821 User manual

1
6821
2 channel transmitter
User manual
2017-01-23
Firmware V1.0-1.6

2
Introduction
The 6821 is a rail-mounted two-channel measurement unit for temperature sensors and other electrical
inputs. The input channels are individual and can be used for different signals. The unit has two analog
outputs or alternatively one analog and one serial output. The serial output accepts Nokeval SCL and
Modbus RTU commands. Up to four logical alarms can control two alarm relays. The inputs are galvanically
isolated from the outputs and the supply voltage, but not from each other.
There are four built-in inter-channel functions: average, difference, minimum, and maximum. More
mathematical and conditional and timed operations may be realized with a simple programming language
called ELo.
The front panel has a four-digit display and four push buttons that can be used to monitor the readings and
to change the settings. The settings can also be edited on a computer using the RS-485 serial connection.
The ELo program can be edited on a personal computer only, not on the front panel.
How to use this manual
The transmitter consists of several quite independent blocks like the two inputs, analog outputs, serial
communications and so on. That is why this manual is also divided in chapters, one chapter concerning one
block.
First read through the chapter ”General” to find out how to mount the transmitter and to open the
transmitter case etc and how to get started with the configuration settings, either with the front panel or
with a PC software. Then advance to the chapter ”Power supply”. To get the transmitter to measure
something, read the chapter ”Inputs”. To get an analog output, read the chapter ”Analog output”, and so
on.
Table of contents
Introduction.......................................................................................................................................................2
General ..............................................................................................................................................................3
Power supply .....................................................................................................................................................7
Front panel ........................................................................................................................................................8
Inputs...............................................................................................................................................................12
Analog outputs ................................................................................................................................................17
Alarms and relays ............................................................................................................................................19
ELo program ....................................................................................................................................................21
Serial communications ....................................................................................................................................24
Specifications...................................................................................................................................................31
Manufacturer
Nokeval Oy
Rounionkatu 107
FIN-37150 Nokia
Finland
Tel [phone]
WWW: www.nokeval.com
Sales & inquiries: sal[email protected]
Technical support: [e-mail]

3
General
Mounting
This transmitter is intended to be mounted on a 35 mm DIN rail. It should be installed on a wall as on the
front cover picture. Other positions will affect the flow of the cooling air and ruin the thermocouple
accuracy. A small air gap to the next instrument on the rail is recommended.
Connections
The connections are explained in the chapters Inputs, Analog outputs, Alarms & relays, Power supply, and
Serial communications.
4 3 2 1
1 2 3 4
4 3 2 1
1 2 3 4
1 2 3 4
6821
85-230 VAC
4 3 2 1
24 VDC/AC
A B
G H
F
Out1 Out Common Out2
A4 3 2 1 B
Out1 Common D1 (A+) D0 (B-)
Power supply Outputs
Relay 1 Relay 2
Alarm relays
Input 1
Input 2
RTD
+
TC, mV, V,
mA

4
Jumpers
To access the jumpers, use a small screwdriver to click the four locks (see
photo). Then pull the top and bottom parts of the case apart. The power
supply must be disconnected to avoid electric shocks.
The picture shows the jumper locations and the default setup. The jumpers
labeled “Free”can be taken off and used where needed.
The jumper positions are explained in the chapters Inputs, Analog outputs,
and Serial communications, pages 12, 17, and 24 respectively.
Configuration settings
There are a plenty of settings that are used to define the operation of the inputs, the outputs, etc. There
are two ways to access them:
On the front panel, see chapter Front panel, page 8.
Using a PC and a serial communications, see chapter Serial communications, section PC configuration,
page 24.
Out1 = mA
Out2 = V
Out2 = mA
Out1 = V
Out2 = 485
Free
485 term
485 floating
Free
Don't use
In1 = mA
In2 pin 1 = +15V
In2 pin 1 = 4W
In2 = mA
Free
See
Analog
outputs
See
Serial
comms
See
Inputs

5
Registers
Analog input x2
In1
In2
Avg
Min
Max
Diff
Built-in functions
Avg
Min
Max
Diff
Analog output x2
@18+=@1
@2>0?2
User program
F1
F2
F3
F12
Serial interface
Scaling Lowpass filter
Alm1
Alm2
Alm3
Alm4
Alarm comparator x4
+
-
Registers
123.4
Display
Relay output x2
OR function
= can be configured to read any
register
Rel1
Rel2
Delay NO/NC
= writes into a register
A1
indicator
Ext1
Ext2
The function blocks of this transmitter –inputs, outputs, etc –are quite independent from each other. The
information between them is exchanged in so called registers. The registers can be seen in the block
diagram above on the gray background. Most of the registers are controlled by some function block. For
example, the register ”In1” is controlled by the first input – there is the input 1 reading.
Registers F1-F12 are controlled by the user program written in the ELo language.
Any register can be used as a ”source” for another block. For example, the analog output 1 can be set to
read the register In1 or any other register. The symbol represents this in the block diagram.
The register values can be viewed with a monitor function, either on the front panel or the PC configuration
program Mekuwin.
Register
Name
Explanation
1
In1
Input 1 scaled reading
2
In2
Input 2 scaled reading

6
3
Avg
Average of the readings, (In1+In2)/2
4
Min
Smaller of the readings In1, In2
5
Max
Greater of the readings
6
Diff
Difference In1-In2
7
Isens
RTD excitation current in mA, normally about 0.25
8
CJ
Internal cold junction temperature in °C
9
Cycle
The measured time to get all the channels, in seconds
10
Out1
Analog output 1 signal in mA or V
11
Out2
Analog output 2 signal in mA or V
12
Alm1
Logical alarm 1 state (0=passive, 1=active)
13
Alm2
Logical alarm 2 state (0=passive, 1=active)
14
Alm3
Logical alarm 3 state (0=passive, 1=active)
15
Alm4
Logical alarm 4 state (0=passive, 1=active)
16
Rel1
Relay 1 state (0=passive, 1=active)
17
Rel2
Relay 2 state (0=passive, 1=active)
18
F1
Free floating point register for ELo programs
19
F2
Free floating point register
20
F3
Free floating point register
21
F4
Free floating point register
22
F5
Free floating point register
23
F6
Free floating point register
24
F7
Free floating point register
25
F8
Free floating point register
26
F9
Free floating point register
27
F10
Free floating point register
28
F11
Free floating point register
29
F12
Free floating point register
30
Ext1
Modbus controlled register
31
Ext2
Modbus controlled register
32
Dch
What to display: 0=Display/Src1, 1=Display/Src1, etc
33
Keys
Front panel key state, see below
Keys register
Keys register gives a sum of the codes of the keys currently pressed:
Key
Code
^
2
v
4
*
8
>
16

7
Power supply
The transmitter 6821 is available for two supply voltage ranges, that are nominally called “24VDC” and
“230VAC”.
6821-24VDC
This model accepts supply voltage of 20 to 28 V DC or AC. The supply is connected in connector A terminals
1 and 2. Either polarity will do.
This transmitter will consume less than 200 mA. However at power-up it will need 500 mA.
6821-230VAC
This model accepts supply voltage of 85 to 260 V DC or AC. The supply is connected in connector A
terminals 1 and 3. The protective earth is not used.
This unit has an internal pre-fuse. If an external one is used, it should be at least 500 mA T.
When wiring, a special attention has to be paid to ensure that accidentally disconnected wires can’t touch
other connectors and cause a risk of an electric hazard. Use e.g. cable ties to group the wires.
4 3 2 1
1 2 3 4
4 3 2 1
1 2 3 4
1 2 3 4
6821
24 V
A B
G H
F
0 V
4 3 2 1
1 2 3 4
4 3 2 1
1 2 3 4
1 2 3 4
6821
230 V
A B
G H
F
0 V

8
Front panel
The front panel can be used to monitor the operation
of the transmitter and to change the settings. It has
several states of operation:
Normal state –displaying the readings.
Configuration state –changing the settings.
Monitor state –displaying the readings and other
variable data.
Normal state
After power-up, the front panel is in the normal state, displaying the input 1 reading (unless otherwise set).
The ”channel” being displayed can be selected using the ^v keys. While changing the channel, the channel
name is displayed until the key is released. Which channels can be selected, depends on the settings
(Display/Src1…4).
The >key can be used to access and change the value of pre-selected registers in order to control the ELo
program (see the Display/Ed settings).
A1 and A2 indicate the states of the alarm relays. They are lit if any of the alarms selected for the relay is
active. The relay NO/NC setting does not affect the indicators.
Configuration state
Entering
Press the *and ^keys simultaneously for two seconds in the normal state to enter the configuration
state. When entered, the Conf led will light. If configuration password is set, it must be entered (Cod.0
displayed). In case the password is not known, switch the power off, hold the *and >keys pressed and
switch the power on again –“PWDC” is displayed briefly. This will also set the serial settings to their default
values.
Navigating
The menu is organized hierarchically. You can move within one menu using the ^v keys and enter a
submenu with the >key. Returning from a submenu is done with the *key. See the menu chart on page
11.
Editing
To see or edit a setting value, press >key.
Most data types are edited simply with ^v keys, finally exiting with *key.
Floating point values, such as scaling and the low pass filter, are edited with ^v> keys: select digit to edit
(blinking) with >and change it with ^v. When the decimal point is blinking, it can be moved with ^v. The
first digit can be replaced by a minus sign.
A1
Conf A2
6800 Series
*
Nokeval
Configuration state
Alarm indicators
Select
Enter
Exit

9
A password is set as follows: push ^to select Set (means password will be used), then push >to enter the
new password. Cod.0 is shown. The password is a sequence of six key presses using all the four keys. Enter
the same password twice; if they match, Set is shown again and you can exit with *. If they didn’t match,
Off is shown. Redo from start. To disable a password, push vto select Off and exit with *.
The math program can’t be edited with the front panel. An RS-485 connection to a computer is required.
Exiting
When all settings are done, exit from the main level of the configuration menu with the *key. Two options
are shown: Save to keep the settings made, and Undo, to discard all changes. Select ^v Save or Undo and
push >.
Monitor state
Monitoring can be used to examine the internal readings, called registers. The built-in monitoring is started
by pressing *and vtogether. Select the item using ^v keys, and finally exit with *.
The registers are explained on page 5.
The last item is Diag. It can be used to see the diagnostic messages. Push >. If nothing happens, then there
are no messages. If happens, try ^v to see if there are several messages. Exit with *.
There are three possible diagnostic messages:
Sensor Fault: some channel has improper connection, over ranging, or a broken sensor or wires.
AD Error: the A/D converter is not working. The unit needs service.
Math Error: there is an error in the math program.
Settings
In the configuration settings menu, there are two submenus concerning the front panel: General, and
Display.
CfCode (General)
This defines a password for the settings. If this is set, the settings can't be accessed without knowing the
password.
To change the password on the front panel, advance to the CfCode setting and push >to edit the value.
Options Off and Set are shown; select Set with the ^v keys. Then push >, and Cod.0 should be displayed.
Now enter six key presses using any of the four keys. Then enter the same sequence another time. If they
matched, Set is displayed again and you can exit with *. Otherwise Off is displayed.
Conf
General
Display
Inputs
Math
Outputs
Alarms
Relays
Serial
General
CfCode
Display
Src1
Dec1
Ed1
Src4
Dec4
Ed4

10
Src1…Src4 (Display)
Display submenu is used to define which readings (or registers) you want to see on the display. Up to four
registers can be selected in Src1..Src4 (the registers are described on page 5). If you do not need all the four
registers, set the rest to Off. After power-up, the register selected in Src1 is displayed, and the others can
be viewed using the ^v keys.
Dec1…Dec4 (Display)
Defines how many digits after the decimal point is displayed on the registers defined in Src1…Src4. Can be
set between -2 and 3. Negative values mean, that the corresponding number of last digits is rounded to
zero. Examples with a reading of 12.34:
Dec=2: ”12.34”
Dec=1: ”12.3”
Dec=0: ”12”
Dec=-1: ”10” (rounded to nearest 10)
Ed1…Ed4 (Display)
If the register selected in Src1 is being displayed, and the user pushes the > key, then the register selected
in Ed1 is displayed and its value can be changed. Likewise while Src2 is displayed, the register selected in
Ed2 can be edited. This way the user can change register values manually and affect the ELo program
operation, control an analog output manually, or quickly adjust the alarm levels.
Other registers than F1…F12 should not be selected in Ed. If the editing is not desired,
set the Ed registers to Off.
When a register value is changed this way, it is stored in the non-volatile EEPROM
memory and restored when the transmitter is powered up next time.
Src1
Src2
Src3
Src4
Ed1
Ed2
Ed3
Ed4
^
v>
>
>
>
*