Monitoring

4-20mA / 0-20mA analog current loop is the output interface of many industrial sensors (water level measurement, current transformers, gas concentration sensors, and so on). The output current is proportional to the measured value.

Connecting a sensor with a 4-20 mA output

• The analog sensor typically has no other power connection (it is powered from the minimum 4mA current).
• HW group converter provides power for the sensor (4mA / max 36V).

Is it possible to use “Sensor 0-20mA 1W-UNI”?

Yes, the HW group “0-20mA” converter can also be used, as long as an external current source is added:

Connecting a sensor with a 0-20 mA output

• Analog sensor (a current probe in this case) does not require external power.
• The HW group “Sensor 0-20mA 1W-UNI” converter does not provide power for the sensor.

How to connect multiple analog outputs

• Converters can be daisy-chained on the 1-Wire UNI bus.
• The number of converters is limited by the maximum number of sensors supported by the particular Poseidon2 or Ares unit.

The SNMP basics

The SNMP (Simple Network Management Protocol) is a way of quick and simple supervision of network elements and services.
                 
It is being increasingly used for monitoring the environment where these elements work. Mainly due to the possibility to monitor the temperature, humidity and other values in the same monitoring software as the other operating parameters of the system. The SNMP was originally designed to be extremely economical and to exist above the UDP protocol. This was to be sure the network management does not put a high load on the network itself. Today in times of gigabite and faster networks the priorities are a little bit different and thus the SNMP got a lot of extensions and improvements.

The SNMP is an asynchronous, transaction-oriented protocol based on the client/server model. The party that sends requests (SNMP client), can be a simple SNMP browser or a complex NMS (Network Management System). On the device side is there is an SNMP agent (SNMP server), that responds to the requests. SNMP traps are an exception and those are sent by agents asynchronously when an event occurs (power failure, fan failure, value excessed, new device discovered…). You need to define the address where the information is sent in advance. The UDP protocol is used to transmit data and it is defined where the applications of individual companies can connect. This is managed by IANA organization (Internet Assigned Numbers Authority - literally: Internet authority for assigning telephone numbers). SNMP can not only be used to read the current values, but also to write the operating values (configure devices).

The SNMP versions

The SNMP Protocol has been developed gradually. The first version (SNMPv1) provides basic SNMP functionality and it is very efficient. As networks were speeding up so was the need for a greater security. Simple authentication was added to SNMPv2 (security with username and password), which followed by adding encryption in the latest version of the protocol (SNMPv3)

In SNMPv1 only Community served for identification of the "authorized" agents. Although the name was user definable, usually only two values are used - "public" for reading and "private" for reading and writing.

The SNMPv2 improved in performance, security, privacy and communication management. The SNMPv2 standard is not much used and is replaced by SNMPv2c, which is compatible with SNMPv1 and has an extended set of commands and a higher efficiency. The SNMPv2u was also not very popular though it was the first attempt to establish SNMP security features.

SNMPv3 is an upcoming variant of the standard and it contains not only the user authentication, but also encrypted communications. For the security Username (similar to Community), Password for authorization (Authentisation password) and key (Privacy password) are used. During the authorization, the communication can be encrypted using MD5 or SHA, private communication can then be encrypted using DES or AES. Starting from SNMPv3 it becomes a full-fledged management protocol in the most demanding corporate networks. The main advantage is that the MIB stays the same and there is no need of any special arrangements during the transition to SNMPv3.

There is an unlimited number of users in the SNMPv3, which allows you to track and log the activity of individual operators. Each user has his combination of Username, Auth. and Privacy password along with the corresponding encryption, which together form a profile.

Using the SNMPv3

The Poseidon2 units now support SNMPv3 and up to 5 user profiles. Please see the images below for examples:

Poseidon2 4002 web interface with SNMP settings

Example of using the SNMPv3 with SNMPget:

C:\Users\volmr\Downloads\SnmpGet\SnmpGet.exe -r:192.168.2.71 -v:3 -sn:public -ap:MD5 -aw:idefix12345678790 -pp:DES -pw:idefix12345678790 -o:.1.3.6.1.2.1.1.3.0

Result:

Example of using SNMPv3 with MGSoft Mib Browser:

Configuration

The result of the Walk command

Frequently Asked Questions

• Can my Poseidon2 support SNMPv3?
  Yes, you must download latest FW and load it to your Poseidon2 device. This can be applied to all models Poseidon2.
   
• Can I load this FW into Poseidon 2250?
  No, Poseidon of first generation can not support SNMP v3.
   
• Are there any changes with structure of SNMP MIB because of support SNMPv3?
  In configuration if you choose SNMP version 1, everything remains compatible with current SNMP interface.

The Poseidon2 and Damocles2 works as a TCP Server at port 502 (Modbus standard). The Modbus/TCP communication takes place using the given addresses. For details, see http://www.modbus.org .

Caution: Modbus/TCP implementation support requires setting the " Slave ID " variable to number 2. Check the setting of this variable in case you are enable to establish a connection. (The actual name may differ in your software – it used to be an address to distinguish multiple devices on a RS-485 line in case of Modbus/RTU).

What you can find in this application note:

• We describe how to properly setup Modbus Poll program version 3.20
• You find out what is possible to read via Modbus/TCP protocol

Notice: Modbus Poll application version 3.20 in its unregistered version works only for 4 minutes after launch. It is necessary to restart the program after to run it again.

Mapping of variables for the Modbus/TCP protocol

Analog quantities
Address	I/O		Type		Functions		Units
100	int		4				Current number of installed (configured in Setup) sensors
101-10x	int		4		0,1°C		Current value of the sensor No. 1 through x, where x is the value at address 100. Units are configured in WEB Setup.
200	int		4		-		Current banknote counters
201 - 2xx	int		4		-		The current counter value, the first counter is at the address 201(H)-202(L), second on 203(H)-204(L) ….
201 - 2xx	int		16		-		Set the current counter value, the first counter is at the address 201(H)-202(L), second on 203(H)-204(L) ….
Digital values
Address	I/O		Type		Functions		Description
100 - 1xx	bit		2		0 - open, 1 - close		Current values of binary inputs
200 - 2xx	bit		1		0 - open, 1 - close		Reads the current value of the output
200 - 2xx	bit		5		0 - open, 1 - close		Sets the value of the output

Inputs registers

Outputs registers

Remote INPUTS

Poll Definition
Slave ID:		2
Function:		02 INPUT STATUS
Adress:		100
Length:		24
Scan Rate:		1000
Auto Read Enable:		Checked

Remote OUTPUTS

Poll Definition
Slave ID:	2
Function:	01 Coil Status
Adress:	200
Length:	4
Scan Rate:	1000
Auto Read Enable:	Checked

Sensors

Poll Definition
Slave ID:	2
Function:	04 INPUT REGISTER
Adress:	100
Length:	2
Scan Rate:	1000
Auto Read Enable:	Checked

The Poseidon2 and Damocles2 works as a TCP Server at port 502 (Modbus standard). The Modbus/TCP communication takes place using the given addresses. For details, see http://www.modbus.org .

Caution: Modbus/TCP implementation support requires setting the " Slave ID " variable to number 2. Check the setting of this variable in case you are enable to establish a connection. (The actual name may differ in your software – it used to be an address to distinguish multiple devices on a RS-485 line in case of Modbus/RTU).

Program Modbus Poll & Damocles MINI

Dry contact inputs - model MINI

Connect the Damocles MINI unit to ethernet and power supply. Launch Modbus Poll application (mbpoll.exe file). In setup menu select option Poll Definition (keyboard short cut F2).

Picture a - Input setting

Setting of inputs in Modbus Poll program (Picture a)

• Slave ID: 2
• Function: definition of running function 02 INPUT STATUS for monitoring of input states
• Address: definition of used variables that will be loaded (for addresses see figure bellow). Beginning at the address 100 - ending at the address 103
• Length: length of loaded variables
• Scan Rate: delay between two following loadings
• Auto Read Enable: to enable automatic reading of values
• Click OK button to confirm

 

Picture b - Network parameters setting

Addresses of inputs in terms of protocol are configured, now set up connection to device itself.

• In Connection menu select Connect (keyboard short cut F3)
• Select TCP/IP
• Set up device IP address and Port (standard is 502)
• Push OK button to confirm

Application is now connected to selected device and in periodic interval loads input values (see the picture c).

 

Picture c - Values loading

Picture d - Damocles MINI - WWW page

>> Damocles MINI
Download and application of Modbus Poll + examples

 

Binary outputs (Damocles MINI)

Open Poll Definition menu to control binary outputs.

Picture e - Output setting

• Slave ID: 2
• Function: definition of running function 01 COIL STATUS for monitoring of output states
• Address: defines the address of used variables that will be logged (for addresses see figure bellow). It begins at the address 200 - ending at the address 201
• Length: number of loaded variables
• Scan Rate: delay between two loadings
• Auto Read Enable: to enable automatic reloading
• Click OK button to confirm

To control binary inputs select option 05 in function menu: Write Single Coil (short cut F7).

Picture f - Output control

You can safe setting of Poll Definition to mbp file to simplify your work. Any time you need it simply load the saved setting.

 

Modbus Poll & Poseidon2 4002

Temperature sensor - model4002

Open Poll Definition in menu.

• Slave ID: 2
• Function: definition of running function 04 INPUT REGISTER for monitoring of output states
• Address: defines address of used variables that will be loaded (for address see figure above).
  • Andrea 100 - number of sensors
  • Addressed 101 - current value
• Length: number of logged values
• Scan Rate: delay between two readings
• Auto Read Enable: to enable automatic reloading
• Click OK button to confirm

Picture ch - Setting of temperature sensor

Two lines are displayed. The first line shows number of connected sensors and the second current temperature with an accuracy of 0.1° C. Save your setting to mbp file to simplify work with Poll Definition. In case you need it, simply load saved setting.

Industrial Bus (RS-485)

• Maximum cable length: 1000 m total
• Number of devices on the bus: Poseidon + up to 31 devices
• Power: 12V/120 mA supplied by the bus, can be boosted with an external adapter (through a S-Hub or a Spider unit).
• Cable type: UTP (2 or 3 pairs)

Topology 1: Basic

• The bus leads via a 4-wire connection from the Poseidon 1250 unit to two daisy-chained sensors, Temp-485 and HTemp-485. Two twisted pairs are used by the connection.
• A S-Hub unit is daisy-chain-connected via the RJ45 jack after the second sensor, using a 4-wire connection from the HTemp-485 sensor. The brown pair is used for power, the blue pair for data.
• Temp-485 and HTemp-485 sensors are connected to the S-Hub connectors 1 through 3 with 6-wire connections (brown pair for power, blue pair leads the bus to the device, green pair back from the device).
• Connector 4 of the first S-Hub unit is used to connect a Spider converter with a patch cable. The Spider unit is used to connect three Temp-1Wire 10m temperature sensors and one door contact (the contact is connected to the blue pair of the RJ45).
• A second S-Hub connects to the Spider unit output via a patch cable.
• Its connectors 1 through 3 are used to connect the Temp-485 and HTemp-485 sensors with 6-wire connections (brown pair for power, blue pair to the device, green pair back from the device).
• Connector 4 is used to connect a Temp-485 sensor with a 4-wire connection (brown pair for power, blue pair for the A/B signals of the bus).
• Termination is enabled at the Temp-485 sensor using the “TERM” jumper.

 

Topology 2: Connecting 10 sensors to IT Bus

Eight temperature sensors and two humidity sensors are connected via the IT Bus (RJ12) to a Poseidon 1250 unit. The 10 sensors are connected using two T-Box hubs and one T-Box2 unit.

• Bus used to connect the sensors: IT Bus

• Total bus length: 10m
• Maximum number of sensors: 10
• Sensors used:
  • 2x Humid-1Wire 1m
  • 8x Temp-1Wire 1m 
• Accessories used:
  • 2x T-Box
  • 1x T-Box2

Conclusion:

This solution is limited by the maximum IT Bus length. It is suitable for applications that use 1 to 10 sensors at one place (one location, 19” rack cabinet, etc.)..

Topology 3: Poseidon Spider – bus converter

The solution combines the properties of both buses. Two Spider units are far apart, connected via a Patch cable with RJ45 modular jacks. Both Spider units connect to four temperature or humidity sensors, each with a 10m cable. One Temp-485 sensor is located at the end of the chain and terminates the bus.

• One Temp-1Wire temperature sensor with a 10m cable is connected directly to the Poseidon unit to the RJ12 jack.
• Six temperature sensors and two humidity sensors are connected via the IT Bus (RJ12) to the Spider units. Each sensor is connected with a 10m cable.
• Two Spider units are connected to Poseidon 1250 with a standard RJ45 Patch cable using the Industrial Bus. Bus length is limited to 1000m.
• The Spider unit comprises 4 inputs for external sensors and supports one sensor per connector – for a maximum of 4 sensors.
• The Industrial Bus is terminated by connecting a Temp-485 sensor with termination enabled over a 4-wire connection. The Spiders have mutually different addresses and are set to the “middle” mode.

• Bus used to connect the sensors: IT bus, Industrial Bus
• Total bus length: 1000m + 9x 10m
• Maximum number of sensors: 40
• Sensors used:
  • 6x Temp-1Wire 10m
  • 2x Humid-1Wire 3m
  • 1x Temp-485
• Accessories used:
  • 2x Poseidon Spider
  • 2x RJ45 Patch cable 300m (RJ45-RJ45)
  • 1x RJ45 TP cable 300m (RJ45-4 pins, “LAST” wiring)

Conclusion:

This solution is not limited by the IT Bus length. The Spider units can be up to 1000m apart. The solution is suitable for large-scale applications with many sensors (e.g. server rooms).

 

Topology 4: Using the Industrial Bus – star topology

This solution demonstrates a star-like connection of sensors to the Industrial Bus using an S-Hub unit. The S-Hub is the central point that connects individual sensors. The maximum bus length decreases to 500m because the cable length of all sensors connected to the S-Hub must be counted twice. A Temp-485 sensor with termination is at the end of the bus.

• One Temp-1Wire temperature sensor with a 10m cable is connected directly to the Poseidon unit, to the RJ12 jack.
• The Industrial Bus connects to the S-Hub input via a RJ45 patch cable. At the same time, the cable powers the sensors as well as the S-Hub; extra power can be supplied by an external power adapter.
  • Sensors must be connected to the S-Hub in a sequence, starting from output No. 1. Outputs cannot be skipped. (For instance, connecting outputs 1,2,5,6 while leaving outputs 3 and 4 unconnected will not work.)
• First three temperature (Temp-485) and temperature/humidity (HTemp-485) sensors are connected in sequence to the first three outputs. An RJ45 / 6-wire cable, wired according to the “MIDDLE” version, is used to connect them.
• The Spider unit is connected with a Patch cord. The Spider connects four Temp-1Wire sensors at 4x 10m distances. The Spider unit is in the “MIDDLE” mode.
• The Industrial Bus is terminated at the Temp-485 sensor connected to the S-Hub at position No. 5. The connecting cable is wired according to the “LAST” version, termination is enabled at the sensor (Term=On).

Topology 5: Using the Industrial Bus – daisy chain

The solution demonstrates daisy-chain linked sensors on the Industrial Bus. Note the distances between sensors. The Spider unit connects four local temperature sensors. At the end of the bus, there is a Sens-UI voltage and current sensor with termination enabled.

• One Temp-1Wire temperature sensor with a 10m cable is connected directly to the Poseidon unit to the RJ12 jack.
• Two HTemp-485 temperature/humidity sensors are connected at the beginning of the bus, using a 4-wire cable connected to the terminals.
• The bus continues to the Temp-485 temperature sensor, still with 4 conductors.
• The Temp-485-Pt100-Cable uses a 4-wire connection as well. The temperature is measured by a Pt100 sensor mounted on a 2m silicon cable.
• The next Temp-485-Pt100-2xDIN converter, mounted on a DIN rail, uses a 4-wire connection. Two external Pt100 thermometers measure two temperature values.
• The following Temp-485-Pt100-Box sensor, designed for external environment, includes a probe for precise temperature measurement. 4-wire connection.
• The Spider unit is, on the contrary, connected via a RJ45 jack. The Spider connects four Temp-1Wire sensors located 4x 10m away.
• Please note the crossing of cables. It is necessary to respect the input and output designation of the RJ45 jacks. The Spider is in the “middle” mode.
• The Industrial Bus finally leads, via a 4-wire connection, to a Sens-UI sensor that measures external voltage and current.
• At this point, the bus is terminated by an external 120 Ohm resistor between the A and B pins.

   

Sources of false alarms

• Contact bounces
• Oscillation of the reading around the threshold
• Changing the connections

The problem is particularly bothering if you use Poseidon with a GSM modem that sends a text message (SMS) to your mobile phone upon each and every alarm.

 

Poseidon supports two functions to avoid false alarms:

• Alarm Notification Delay
• Hysteresis Idle Range

 

Alarm Notification Delay

The Alarm Notification Delay function prevents an alarm alert from being sent if the alarm lasts only for a very short time. The same delay is applied to alarm activation and alarm deactivation alerts.

• Blue color indicates the behavior when Delay [s] = 0.
• Orange color indicates the behavior when Delay [s] = 20.

Hysteresis / Idle range

The Hysteresis setting defines a tolerance band for suppressing alarm alerts. The function prevents multiple alarm alerts if the reading oscillates around the specified threshold. The range is configured independently for each sensor.

 

The figure demonstrates two cases. Without the hysteresis idle range of 5°C, the alarm raised in point 8 would end in point 9; however, the hysteresis function keeps the alarm active until the temperature reaches the upper limit of the tolerance band (point 10): 5℃ + (–15℃) = –10℃.

• Hysteresis = 5°C:   
  The unit sends 3 e-mail (SMS) messages
  Alarm active in points 0..4,  8..10, 12 and beyond
   
• No hysteresis (0°C):   
  The unit sends 8 e-mail (SMS) messages
  Alarm active in points 0..1, 2..3, 8..9, 12..13, 14 and beyond

Technical description

• Power consumption is measured by ABB DHM13007 and DBM23000 M-Bus digital power meters.
• One phase ABB ODIN single power meters are connected through the OA1408 serial to M-Bus converter.
• Each electricity meter provides voltage, current, power factor, energy, kWh and other available values.
  All values are readable via SNMP, Modbus/TCP, XML and other protocols.
• Electricity meters are connected by M-Bus to HWg-PWR 25 (smart M-Bus to LAN gateway).
• Autodetection can identify connected M-Bus meters.
• All M-Bus meters are powered from the HWg-PWR 25 device.
• The HWg-PWR smart M-Bus to ethernet gateway sends an alarm in the event of failure or value out of a specified range (E-mail, SNMP Trap, SMS over SMS GW).
• You can connect an external SMS Gateway for simple SMS alerting without any software.
• PDMS can export energy consumption to MS Excel even for every single minute.

HWg-PDMS software: Energy in graphs & MS Excel

• HWg-PWR 3/12/25 gateway can be connected to the PDMS software directly over LAN or by email.
• Variables can be analyzed in the HWg-PDMS software.
• Graphs can be viewed directly in HWg-PDMS.
• Measurements can be exported using the XML interface.
• Measurements can be imported to MS Excel for further processing.