Nokeval FT20 User manual

Nokeval
FT20
User Manual

2
Contents
Document information...................................................................................................................................... 2
Introduction....................................................................................................................................................... 3
Trademarks........................................................................................................................................................ 3
Manufacturer .................................................................................................................................................... 3
Installing ............................................................................................................................................................ 4
Maintenance...................................................................................................................................................... 8
Firmware settings .............................................................................................................................................. 9
Operation......................................................................................................................................................... 14
SCL protocol..................................................................................................................................................... 15
Modbus protocol ............................................................................................................................................. 16
Nopsa commands ............................................................................................................................................ 19
Specifications................................................................................................................................................... 23
Document information
Device Scope: FT20
Device Versions: 1.1 to 1.2
Document Type: manual
Document ID: 2873
Document Version: 17
Document Date: 2.10.2012

3
Introduction
FT20 is a radio data receiver and repeater for Nokeval MTR, FTR and KMR series wireless transmitters.
Type FT20-RTC433-RECEIVER means the device is pre-set as receiver only. Type FT20-RTC433-REPEATER
means the device is pre-set as repeater and is supplied with a power supply.
FT20 receives and buffers the data packets that wireless transmitters have sent. It can also relay the data
packets so that large areas can be covered using only one receiver. It automatically recognizes the types of
the transmitters, so different kinds of transmitters can be used simultaneously. Transmitters can also have
different transmission intervals. FT20 uses license-free 433.92 MHz frequency band (ISM) so it can be freely
used, for example, almost in whole Europe.
FT20 is housed in a watertight (IP 66) and impact resistant plastic enclosure. The joint between the two
modules is sealed with two rubber O-rings. The receiver is connected to a computer using RS-485 bus and it
requires e.g. PromoLog data acquisition application that reads the data from the device.
Nokeval SCL or Modbus RTU protocol is used for data transmission between the receiver and the computer.
Multiple receivers can be connected in parallel to an RS-485 bus to increase the coverage area. FT20 has
one diagnostic LED and it requires 8..30 VDC power supply.
Trademarks
This device uses the FreeRTOS real-time operating system version 6.0.5. The source code of the RTOS is
available on request –contact [e-mail].
Manufacturer
Nokeval Oy
Yrittäjäkatu 12
FI-37100 Nokia
Finland
Tel [phone] (Mo-Fr 8:30-16:00 EET)
WWW http://www.nokeval.com/
email [email protected]om,
[email protected]m

4
Installing
Mounting
The best installation environment for a radio receiver is above a big grounded horizontal metal surface
surrounded by as few as possible vertical metal surfaces. Antenna is to be installed perpendicular to the
metal surface. The best range for the transmitter is achieved when there is a line-of-sight from the receiver
to the transmitter. Walls and objects between the transmitters attenuate the signal and thereby shorten
the range. On the other hand, metal surfaces cause reflections which might lengthen the range.
Placing the repeaters
The repeater must be placed in the coverage area of at least one receiver. For example, in the picture
below the whole warehouse is covered using two repeaters that are placed near both ends of the
warehouse. In this way the receiver that is placed in the center of the warehouse can receive transmissions
anywhere from the warehouse.
RS-485
Repeater Repeater Receiver
50..200 m
Coverage area
Warehouse

5
Using two repeaters
The picture below shows how two repeaters can be daisy chained.
RS-485
Repeater Repeater Receiver
50..200 m
Coverage area
Warehouse
The downside of daisy chaining is that now both repeaters relay also the data that they receive from the
other repeater. This increases radio traffic and therefore decreases the maximum allowed number of radio
transmitters in a coverage area. See the transmitter’s manual or example table on page 6 how the use of
repeaters affects the maximum number of transmitters.
Both repeaters can be placed in the coverage area of one receiver like in the example picture below.
RS-485
Receiver
Warehouse
Repeater
50..200 m
Coverage area Repeater

6
The maximum number of transmitters
The maximum number of radio transmitters in a coverage area is limited by radio standards. The use of
repeaters reduces the maximum number of transmitters because repeaters use the same frequency
channel as transmitters. The following example table shows the allowed maximum number of Nokeval
radio transmitters in a coverage area.
Transmission
Interval (s)
Receiver
Receiver and
1 repeater
Receiver and
1 repeater
Maximum number of transmitters
5
22
11
7
10
43
22
14
20
87
43*
29
30
130
65
43
40
174
87
58
50
217
109
72
60
261
130
87
70
304
152
101
80
348
174
116
90
391
196
130
120
522
261
174
240
1043
522
348
For example, if you have transmission interval of 20 seconds and one repeater, the maximum number of
transmitters is 43*.
Note: ID filter can be used to reduce the radio traffic caused by the repeaters. Using ID filter, only the
desired transmitter data packets is repeated (see the section "Firmware settings" sections Repeater/ID
filter and Channels/Repeater).
Enclosure
FT20 consists of a radio transceiver module (FT20-RTC433) and a processor/serial module (FT20-RS485).
Before use, please make sure that the modules are pushed together all the way so that the locking latches
snap into position.

7
Opening the case
Modules can be detached from each other by pressing the locking latches on the sides of the enclosure and
at the same time pulling the modules apart.
For receiver operation the serial module must be opened for RS485 and power
cables installation. Serial module can be opened by gently pushing a screwdriver
into the slot that holds the cover plate.
When the cover plate is removed, the circuit board can be pulled out of the
enclosure.
Connections
2
3
4
1
RS-485
Power
8...30 VDC
+ - D1 D0
POL
Jumpers
Diag. LED
Default RS485 settings
RS485 AC term.
Repeater Transmit.
LED
FT20 serial module has a 4-pin terminal block for power supply and RS-485 connection. Serial module
features also a round 3.5 mm POL programming connector jack found on many other Nokeval products as
well. FT20 radio module contains BNC type antenna connector.
Power supply
The supply voltage range is 8...30 VDC and is connected to terminals 1 (+) and 2 (-). Power demand is 50
mA. FT20 is protected against wrong polarity of the supply voltage.
RS-485 serial bus
RS-485 is used when the device operates as a receiver. RS-485 interface can easily be added to a computer
by using Nokeval DCS770 or DC771B USB - RS-485 converter or RCS770 USB/RS-232-RS-485 converter. If
you use DC771B converter, no external power supply needed (DC771B's power supply should be set to
10V). RS-485 bus is connected to terminals 3 (D1) and 4 (D0). The supply voltage's negative terminal 2 (-)
can also use as ground for RS-485.
The RS-485 bus consists of a bidirectional half-duplex twisted data pair and a common wire. The cable
should be shielded, the shield earthed at one point. The nominal impedance should be approx. 100-120 Ω.
The length of an RS-485 bus can be up to 1 km and it can be connected to 32 devices, more can be
connected via bus repeaters. If the bus is long (say more than 100 m), it is recommended to terminate the
first and last device on the bus (set the ”RS485 AC term” jumper to ”on” position).
The polarity of the data pair is important. Modbus specifications call the positive idling line D1, but it is also
commonly known as +, B, and A. Correspondingly the negative idling line is -, A, or B.
The bus needs one device that gives a small voltage between the data wires when no device is transmitting
on the bus. This is called biasing or fail-safing. The master device is usually the natural choice for biasing.

8
POL connector
The POL connector is convenient for configuring when the device operates as a repeater. This connector
can be used when the modules are disconnected from each other. Note that when the POL plug is
connected the RS-485 bus is disabled.
Two types of programming cables are available:
•POL-RS232 for the RS-232 port of the computer.
•DCS772 for the USB port of the computer (recommended).
Antenna
Antenna is connected to the transceiver modules’s BNC connector. Antenna is first pushed into the BNC
connector by aligning it with two guide posts after which it is turned 90 degrees clockwise. Antenna can be
removed by turning it counterclockwise after which the antenna can be pulled off.
Jumpers
FT20 has three jumpers in the serial module: ”RS485 AC term”RS-485 termination jumper, default serial
settings jumper and jumper which turns repeater on or off (if enabled in firmware settings).
If the device is the last device on the RS485 bus and the bus is long (say more than 100 m), it is
recommended to set the ”RS485 AC term” jumper to ”on” position. When this jumper is set, AC
termination is used which means that 1 nF capacitor and 110 ohm resistor are connected in series between
the bus wires.
Maintenance
Cleaning
The plastic parts can be cleaned with a soft cloth and soap water. The cloth must be damp but not wet.
Cleaning with isopropyl alcohol is also allowed.

9
Firmware settings
Repeater mode
User does not normally need to setup the device. By default, the device type FT20-RTC433-REPEATER is
setup as repeater (repeater jumper is on) and it repeats all the received data packets. In some special cases,
for example, when there is lot of transmitters, ID filtering may be needed.
Receiver mode
If you use PromoLog data acquisition software, then there is generally no need to configure the device. Just
check that the repeater jumper is off because the repeater mode is not needed and thus prevent the extra
radio traffic.
Mekuwin
MekuWin can be used to change settings on various Nokeval products. It has a unique feature: it loads the
structure and the contents of the configuration menu from the target device, so the same MekuWin
version can be used with past and forthcoming products. There is no need to update this software every
time a new product or product version is released. You can download Mekuwin from Nokevals web site for
free. Mekuwin has its own instruction manual.
It is also possible to change the configuration settings remotely by writing to the appropriate Modbus
Holding registers.
With a POL programming cable
The communications parameters for POL are always:
Protocol
SCL
Baud
9600
Parity
8N1
Address
0
Over the RS-485 serial bus
The Mekuwin communications parameters must match the selections made in the device (Serial menu).
Resetting RS-485 serial communication settings
In case RS-485 serial settings are for some reason not known, they can be temporarily set to defaults by the
“default RS485 settings” jumper (shown in the figure on page 7) when the device is powered up.
Default communication parameter settings:
Protocol
SCL
Baud
9600
Parity
8N1
Address
0

10
Serial
Protocol
Baud rate
Bits
Address
Configuration settings
The configuration settings are arranged as a hierarchical tree: The Conf menu has submenus, and these
contain settings and possibly more submenus, etc.
Menu of the FT20:
Conf
Serial
Channels
Repeater
Advanced Options
Advanced Options
Weak repeater filter
Compatibility mode
Repeater
Repeater
ID filter
Extra bytes
Max jumps
Replace with RSL
Ch1
ID
Value
Reading
Info
Repeater
Serial
Protocol
Baud rate
Bits
Address Channels
Timeout[min]
Count
Ch1
Ch2
Ch3
Ch4
Ch5
Ch6
Ch7
...
Ch100
Serial submenu
Serial communication settings.
Protocol
•SCL: Nokeval SCL protocol. Default.
•Modbus RTU: Modbus RTU protocol
Baud rate
Baud rate selection: 300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200, 230400.
Default 9600.
Bits
Bit selection: 8N1, 8N2, 8E1, 8O1.
Note! SCL protocol uses always 8N1 (this item does not appear when the protocol is SCL). Modbus RTU uses
commonly 8E1.
Address
Serial communications address selection. Since several devices can be attached to a bus, each device needs
to be configured to a different Address. Valid SCL-addresses are 0...123. Valid Modbus RTU-addresses are
1...247. Default 0.