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Introduction and overview

This document covers the operation and interface definition of the Panoramic Power Bridge when working in the stand-alone mode.  In this mode, the Bridge implements a Modbus TCP/RTU protocol which sends sensor’s current readings to a local server. The local server acts as a Modbus master server and the Bridge acts as a Modbus TCP/RTU slave. 

The image below depicts a typical network diagram for a Bridge operating in the stand-alone mode:

• Sensors transmit readings once every 10 seconds to the Bridge via proprietary wireless communications.
• For each configured sensor, the Bridge stores the last received measurement in memory. It will be stored until overridden by a new measurement from the same sensor or until the Bridge resets.
• A Modbus TCP/RTU master device (typically a computer or PLC) connects to the Bridge via local area network (LAN) or RS485 cable and polls the Bridges for sensor data. 
• The Modbus master device can connect to multiple Bridges, each of them receiving multiple sensors.
• Bridge configuration is done via the Bridge’s built in web server, using the web browser of a laptop connected in the LAN. 

Figure 1: Network diagram

Hardware & Networking requirements

Supported Hardware

• Sensors: PAN-10, PAN-12, PAN-14 and PAN-42.
• The Modbus interface also supports reading the Bridge’s pulse inputs (Gen4 and above)
• The Modbus TCP solution is supported by Gen3 and above and requires firmware v470 or higher. To support PAN-42 sensors, and/or RTU interface, firmware v476 is needed.
• In stand-alone mode, each Bridge supports up to 32 data points (A single phase sensor or a phase in a 3-phase sensor).

Supported LAN networks

To work in the Modbus TCP mode, the Bridge must be set-up for Ethernet connectivity. A Bridge configured for cellular network connectivity supports Modbus RTU but does not support Modbus TCP. 

Assigning a fixed Bridge IP address

For Modbus TCP to operate properly, the Modbus master must be able to repeatedly reach a specific Bridge via its IP address or DNS name. The solution requires a fixed static IP address assigned to the Bridge. This can be done by selecting ‘fixed IP’ in the Bridge network settings, or alternatively using DHCP but ensuring that the DHCP server always assigns the same IP address to the specific Bridge.

Assigning a Slave address

For Modbus RTU to operate properly, the Bridge is assigned a Base (slave) Address and the Modbus master must have a list of all the monitored Bridges and their Base Addresses (in the range of 1 to 247).

Bridge configuration

Bridge configuration is done from a laptop’s web browser using the Bridge built-in web server. 

Initial Bridge configuration, including setting up a fixed IP address to be used later, is done via a directly connected laptop. Please see ‘Accessing the Bridge web interface’ section in the Gen 4+ Bridge Manual. 

Once a fixed IP has been assigned to the Bridge and the Bridge Admin UI Availability in the Bridge Configuration screen is set to Always, further configuration can be done by navigating to the Bridge IP address from a web browser. The laptop used for such configuration must have HTTP route to the Bridge.   

NTP requirements

To operate properly, the Bridge needs to get the real time clock (RTC). Since the Bridge has no battery-powered hardware RTC, it gets the time using a standard NTP server.

The Bridge gets the NTP time, as part of the boot process, using the following process:

• If a dedicated NTP server IP is defined, it will try to get the time from that server
• Alternatively, it will try to get the time from a list of well-known public NTP servers
• If both options above fail, it will get the time from the cloud-based server.

Option 3 above only works in ‘Connect to PowerRadar mode’ or ‘combined mode’ (See ‘Connection Setup’ section below). Therefore, when working in ‘Stand-Alone Modbus TCP’ mode an NTP server must be defined in the LAN or alternatively, NTP outbound access to public servers must be implemented in the firewall.

Another option is to set the real-time clock via the Modbus Interface (by writing to registers 1-2. see Table 1). This will override any time retrieved during the boot process. 

Modbus parameters

These parameters are needed when setting up the connection from the Modbus Master:

The Bridge Modbus TCP interface is enabled via TCP port 502

Recommended timeout value for the Master is 5 seconds.

Little endian Byte swap word order is used

For Modbus RTU mode an RS485 interface set to 38400 Baud, 8 data bits, No parity, one Stop bit and no handshake (No DSR, CTS, DTR, RTS). Request messages can get Responses of up to 125 data registers. See the Gen 4+ Bridge Manual for details of the Bridge Modbus (RS485) connector. Note: A USB to RS485 can be used for the RS485 interface.

Bridge Modbus Software Model

Modbus Register Map

This section is for use by the Modbus Host programmer. The table below shows the Bridge register map as reflected to the Modbus Master:

Table 1: Bridge Register Map

The map contains 4 main areas:

• Bridge date/time settings – Holding registers 1-2 - This is where the Modbus host can set or read the Real-Time Clock of the Bridge. It can be used if there is no RTC server reachable by the Bridge. 
• Bridge information – Input registers 1-12 - Table 1.1 - Various Bridge status data
• Sensor readings – This is where the sensor readings are retrieved. 
• There are 3 tables with sensor readings: (N = slot number 0 to 31)
  • Table 1.2 – Input registers 2001-2010 +20N – Sensor main readings – An array of 32 slots x 20.
  • Table 1.3 - Input registers 3001-3004 +4N – Extended parameters - Array of 32 slots x 4 registers each
  • Table 1.4 - Input registers 3501-3518 +18n – Additional parameters – Array of 9 slots x 18 registers each (for up to 3 PAN42 sensors). Here n = 0-8 (additional_idx–1 from table 1.3)
  •      NOTE: For the additional parameters of a PAN42 sensor, use the additional_idx from table 1.3 to get the associated entry in table 1.4. 
    Additional parameters: Table 1.4(n), where n = Table 1.3(additional_idx – 1)    (range 0-8)
• Pulse Counter #1 and #2 Readings – These holds the counters for the two pulse inputs of the Bridge. Tables 1.5 and 1.6 – Input registers 5001-5005 for Pulse counter #1, Input registers 5006-5010 for Pulse counter #2.
  Note: the bridge counts both rising and falling edges of the pulses. It means that for a device with a KY output, the count should be divided by 2.
• PAN42 EEPOROM error reports – The PAN42 uses an EEPROM to save the energy counters. It saves the counters every 20 seconds. In case of power shortage, when the power is back, the last saved values are restored. If the reading from the EEPROM or writing to EEPROM fails, the PAN42 sends an error report (error 1 or 2). The energy counters roll over when the value exceeds the 32-bits size (0xFFFFFFFF to 0). In this case it sends an error report 3. The user can reset the counters by pressing an internal pushbutton (see the PAN-42 User Manual). This action sends the error report 4.
  
   

Sensor slot allocation example 

The following image depicts an example of how the sensor software model works:

Figure 2: Software model example

In the example above:

• Only two of the 32 Bridge slots have been assigned to sensors.
• Slot #1 has been assigned to sensor S/N 12345678
• Slot #2 has been assigned to sensor S/N 12312312
• Slots #3-#32 have not been assigned with any sensors and remain empty. 
• Whenever a sensor message from one of the two sensors (12345678 or 12312312) is received, the sensor-data section of the table will be updated. The update will override the previous data.
• We can also see another sensor (S/N 55555555) which is received by the Bridge but has not been allocated to any slot. This sensor data will be ignored when the Bridge is in Modbus TCP mode. 
  In ‘Connect to PowerRadar mode’ or ‘combined mode’ all sensor data is simultaneously sent to the cloud-based server regardless of the assignment. 

Sensor Readings

As seen in Figure 2 above, each sensor slot contains sensor data. This section will review and explain the sensor data stored for each slot.

Figure 3: Sensor data storage

As seen in the image, each sensor slot reserve 40 bytes of memory and store the following values:

• Status – Indicating the status of the reading of the specific slot.
• Sensor S/N – This is the serial number of the sensor associated with this slot
• Timestamp – A UNIX Epoch timestamp of the latest message received from the sensor. It is the number of seconds that have elapsed since 00:00:00 Thursday, 1 January 1970, Coordinated Universal Time (UTC), minus leap seconds.
• Current [A] – The calibrated current (in A) measured in the last sensor message received.
• RSSI – an indication of the RSSI (signal strength) of the last measurement in dBm.   

When reading the data, the status register should be analyzed first. Based on its content the other registers should be processed as shown in the table:

Table 2: Sensor Status

Pulse counter registers

Gen 4 Bridges (and above) support two pulse inputs. The Bridge counts the pulses on each of the inputs and provides this data in the registers. 

Sensor Calibration keys (not PAN-42)

Each Panoramic sensor is calibrated during manufacturing and a unique calibration key is generated for every sensor. This key is used to calibrate the sensor raw measurements to achieve optimal accuracy. 

When working in Connected to PowerRadar mode, raw measurements are calibrated in the cloud. In stand-alone mode, however, the calibration is done on the Bridge itself, utilizing a unique calibration key.

The calibration key is a sensor specific, 15 alpha-numeric string (e.g. ACD43-XU3V5-Z7RF3), which must be provided when allocating a sensor to be used in stand-alone mode and dual mode. 

To get a calibration key for a specific sensor use one of the flowing options:

• Automatically calibration key retrieval - if the laptop used to configure the Bridge has Internet access, a calibration key can be automatically retrieved when defining the sensor in the Bridge. This is the easiest and most efficient way to get the calibration key. Internet access is only required for the laptop used to set the Bridge and only during the configuration. 
• Manual calibration key retrieval – In the rare case where internet access is not available during Bridge configuration, please contact Support by opening a ticket at www.powerradar.energy/support and provide the serial numbers of sensors needed. A file containing the respective calibration keys will be provided to be manually entered into the Bridge.

Bridge Configuration for stand-alone mode

To work in the stand alone-mode the Bridge must be configured via the built-in web interface. This is explained in detail in the Gen 4+ Bridge Manual. 

Connect to the Bridge web interface 

Initial Bridge configuration is done by forcing the Bridge into configuration mode and directly connecting a laptop with point-to-point ethernet cable.

The full process is defined in the ‘Accessing the Bridge web interface’ section in the Gen 4+ Bridge Manual. 

Set networking mode 

1. Navigate to the ‘Network Setup’ tab and set the Bridge networking mode
2. Note that only ‘Ethernet’ networks support the stand-alone Modbus TCP mode. Stand-alone Modbus RTU mode can work alongside any network mode.
3. Set the IP configuration for the Bridge. A static IP (or DHCP with fixed IP guarantee) must be used in stand-alone mode to allow the master Modbus TCP to repeatedly address this Bridge. 

Figure 4: The Network Setup Screen

Set Connection mode 

1. Navigate to the ‘Connection Setup’ tab to set the Bridge connection preferences. 
2. By default, the Bridge is configured to “Connect to PowerRadar”
3. Check ‘Enable Stand Alone Modbus mode’ to enable the Modbus mode option. 
4. Check ‘Modbus TCP’ to enable the Modbus TCP option, or ‘Modbus RTU’ to enable the Modbus RTU option.
5. For the Modbus RTU option, enter the ‘Modbus Base Address’ (1 to 247).
6. Set the RTU port speed (bps) from the dropdown menu.
7. Note that it is possible to set both ‘PowerRadar’ and ‘Modbus’ modes concurrently. In this case:
   1. The Bridge will send sensor data to the cloud-based server (all received sensors).
   2. In parallel, it will make sensor data available for Modbus (allocated sensors only).

Define Bridge UI accessibility

For enhanced security, the Bridge UI is accessible by default only during configuration mode, using a wired-connected laptop. 

It is possible to change that configuration, making the UI accessible from any laptop in the same LAN as the Bridge. While less secure, this mode can be useful during testing and sensor setup when multiple frequent changes are made to the Bridge UI. Setting up a unique administrator password is strongly recommended. 

1. Navigate to the ‘Bridge Configuration’ tab 
2. Choose Bridge UI accessibility:
   1. Choose ‘Only in config mode’ for maximum security – In this mode the Bridge UI is only accessible from laptop with direct Ethernet connection and only when the Bridge is placed in Configuration mode.
   2. Choose ‘Always’ for maximum flexibility – In this mode the Bridge UI is available from any device with Bridge network access. This mode is recommended only during setup period and after a unique administrator password is set.

Figure 6: Bridge Configuration

Assign sensors to slots

Any sensor to be used by the Modbus interface must first be allocated to specific location (slot) within the Bridge. Once allocated, this sensor readings are guaranteed to always be in a fixed register address.

Figure 7: The Sensors Tab

Assign a sensor to a slot

1. Navigate to the ‘Sensors’ tab 
2. Choose an empty slot and press the ‘+’ icon. For PAN42 sensor, make sure the following two slots are also available (PAN42 sensor requires 3 empty consecutive slots).
3. 

Figure 8: The Sensor type select menu

4. For PAN10, PAN12 and PAN14:
   1. Choose Sensor.

Figure 9: Add Sensor Pop-up

b. Type the sensor’s serial number.
c. Type the calibration key if you have it or click ‘Get calibration key’ to have it automatically retrieved and inserted (The web site must be reachable from the configuration laptop).
d. Press the Save button.

Figure 10: Add PAN42 Sensor Pop-up

a. Type the sensor’s serial number. The sensor is registered in 3 slots (for 3 phases)
b. Press the Save button.

 The sensor is now assigned to the slot. New readings will be shown in this screen and made available via the Modbus TCP/RTU interface.

Note 1: Stand-alone mode supports the following sensor types: PAN10, PAN12, PAN14 and up to 3 PAN42 sensors.

Note 2: The calibration key is a unique, per-sensor, value used by the Bridge to calibrate each reading for accuracy. It is a mandatory, sensor specific, value. PAN42 does not need calibration.

Note 3: When clicking ‘Get Key, your browser communicates with the platform to get the calibration key. It is, therefore, essential that the laptop has Internet connectivity.

Note 4: If having issues retrieving the calibration key, please contact support who can provide an offline list of calibration keys to be entered manually.

Delete a sensor from the list

To delete a sensor from the list, press the Trash-Can icon at the beginning of the line. Confirm the delete.

You can delete a PAN-42 sensor by pressing the Trash-Can at any of the 3 sensor lines, all 3 lines will be deleted.

View Sensor Readings

Sensor readings are available in the ‘Sensors Tab’. Each allocated sensor will display the last received reading. A new reading will override the previous reading. 

1. Navigate to the ‘Sensors’ tab. This Tab is accessible only when ‘Connection Setup’ > ‘Enable stand-alone Modbus mode’ is checked.
2. Allocated slots will show the following values for PAN10, PAN12, PAN14 and PAN42:
   1. Sensor S/N: The serial number of the allocated sensor
   2. Current [A]: The last calibrated measurement in Ampere. 
   3. RSSI [dBm]: The received signal strength of the last measurement. 
   4. Timestamp: the time of last measurement.

Note 1: The current readings shown here have already been individually calibrated by the Bridge for accuracy, using the calibration key.

Note 2: PAN10 and PAN12 current readings can be used as-is. For PAN14, these values should be multiplied by the CT-Rate of the CT used. 

For PAN42 the table will show the following additional values:

1. Voltage [V]: The last measurement in Volts RMS
2. Active Power [W]: The last measurement in Watts
3. Reactive Power [VAR]: The last measurement in VARs
4. Power Factor: The last measurement power factor
5. Frequency [Hz]: The last measurement in Hertz

Figure 11: Sensor’s list – Main values

Scroll Right for additional readings:

Configure the Bridge Pulse interface

1. Navigate to the ‘Pulse Setup’ tab 
2. Enable pulse input 1, 2 or both
3. Enabled pulses are made available for Modbus TCP/RTU based on the ‘Connection Setup’ > ‘Enable stand-alone Modbus mode’ value and are sent to the cloud-based server based on the ‘Connection Setup’ > ‘Connect to PowerRadar’ value.
4. Pulse inputs are of type KY (2 terminals) but the counter counts both the Rising and Falling edges of the pulses. If the connected device is of type KY, you need to divide the reported counter value by 2. If the connected device is of type KYZ, connect either the K and Y terminals or the K and Z terminals. You do not need to divide the reported counter value by 2.

Figure 13: Pulse Setup Tab
 

Bridge LED configuration for stand-alone modes

The Bridge contains three hardware LED indicators that change based on Bridge operations. 

In a ‘Standalone mode’ the Bridge’s middle LED (link state LED) supports the following behavior:

Modbus TCP mode:

• Slow 1-sec Yellow blinking until local network connection is established (same as in ‘Connect to PowerRadar’ mode). A solid Green when done.
• Green, faster 0.4-sec blink if local network connection is established but no Modbus connection from a master device detected. 
• Solid green when a Modbus master device connection is detected.

Modbus RTU mode:

• Solid green when a Modbus master device Request messages are detected.
• Green, faster 0.4-sec blink after about 45 seconds of no Modbus master device requests. 

In a ‘Combined’ mode (Cloud-based Server and Modbus)

For communication with the network, there is no change in LED behavior when in ‘Connect to PowerRadar’ or ‘Combined’ modes. The Green LED shows the Communication with Modbus Master as described above, in parallel with the Network.