Laurel Electronics Ethernet Node Configuration for Series 2 Digital Panel Meters, Counters, Timers, Transmitters and Ethernet-to-Serial Device Servers User Manual
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assigns a Private IP address to each device on the network. Built-in DHCP server capability allows
Nodes to constitute themselves into a network and be connected directly to a host computer when
no router or dedicated DHCP server is present. The time for Nodes to decide that there is no
dedicated DHCP server is about 25 seconds. The Nodes are intelligent enough that when another
DHCP server comes online, the temporary DHCP server Node relinquishes its unique status and
seamlessly becomes a client network device.
On a Local Area Network (LAN) where the host computer is part of the network, the Nodes are
discovered by our Node Manager Software, which then lists the Nodes’ MAC address and private
IP address. When one of the discovered Nodes is selected, all of the active devices on that Node
are discovered, and the following information is listed for each device: device name, address, type,
revision, signal conditioner, protocol, communication settings, and reading format.
On a Wide Area Network (WAN), such as the Internet, the host computer is outside of the LAN
and therefore must know the public IP address of the LAN router to discover the Nodes on the
LAN.
Emails with device readings and alarm status can be sent to a computer or to a smart phone in
the form of text messages when devices on a Node encounter an alarm condition, go on- or off-
line, or at selected intervals. Emails containing device readings can also be sent from the Node in
response to email requests. Each Node can be configured with an email account, recipient email
addresses, and notification intervals. Emails can be sent as text messages to any smart phone to
notify plant operators of alarm conditions wherever they are.
Communication protocols supported by our Nodes are Modbus RTU, Modbus ASCII, Custom
ASCII (a simpler protocol than Modbus), and Modbus TCP for Ethernet communications. When
used with an LNET485 or LTNET485 Ethernet-to-serial device server Node, Modbus TCP is
seamlessly converted by the Node to Modbus RTU or Modbus ASCII for communication with
meters and transmitters on an RS485 bus.