Smart 1-Line
TM
Page 17
3.1.2.11 Modbus Server Settings
These settings only need to be adjusted if the Smart 1-Line will provide Modbus data to other
equipment or systems. Otherwise, the default settings should be used.
If the trip units are connected to the Smart 1-Line via RS-485, the Smart 1-Line can serve data to
“other systems”, via its internal Modbus Server application. If “other systems” will obtain data from
the Smart 1-Line, the Modbus Server settings will need to be changed.
Max Number of Clients:
This setting determines the maximum number of “clients” that will be allowed to request data from
the Modbus Server. Internally, the Smart 1-Line has 2 clients, and thus the minimum (and default)
setting is 2. If “other systems” will be obtaining data from the Smart 1-Line, the number needs to be
incremented for each additional system.
If a “local” and a “remote” Smart 1-Line will be connected to the same system,
this setting should be 4.
Max Number of Queued Messages:
This is an advanced setting. The Modbus Server receives messages from Modbus Clients and
sends them to Trip Units over RS485. If a new message from a client is received before a Trip Unit
responds, it’s queued and, after the Trip Unit response (or timeout), sent to a Trip Unit. Modbus
Server can queue up to “Max Number of Queued Messages”. After that, new messages from
Modbus Clients are ignored.
Modbus Port:
This is an advanced setting. Well-known TCP port 502 is reserved for the Modbus Application
Protocol. Avoid any other well-known ports. Make sure there are no conflicts if using a port other
than 502. Refer to “Service Name and Transport Protocol Port Number Registry” at
https://www.iana.org/assignments/service-names-port-numbers/service-names-port-
numbers.xhtml
https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml
Trip Unit Response Timeout
:
Adjusts how long the Modbus Server will wait for a reply from each trip unit.
Figure 17: Modbus Server Settings
