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:
1. If a dedicated NTP server IP is defined, it will try to get the time from that server
2. Alternatively, it will try to get the time from a list of well-known public NTP servers
3. If both options above fail, it will get the time from PowerRadar.
Option 3 above only works in ‘PowerRadar connected 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
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.
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