Echelon SmartServer 2.2 - Manual (Page 272)

SmartServer 2.2 User’s Guide 273
network messages are not sent to them. This ensures that network
performance is not impacted by an offline Modbus device.
You can also set the minimum period of time (in seconds) that the
SmartServer waits before transmitting network messages to offline
Modbus data points. During this period, an offline Modbus device
transmits an OFFLINE status in response to data point requests. Once the
Minimal Offline Time elapses, the SmartServer sends a read/write
request to one offline Modbus data point. If the read/write request
succeeds, the Modbus data point and its Modbus device are marked
online, and all cached read/write requests for the offline Modbus data
points on the Modbus device are executed.
The default Use Minimal Offline Time for a Modbus channel is 60
seconds.
Modbus Network
Property
Data Rate Select the bit rate at which the SmartServer will communicate with the
Modbus devices on the channel. The default value is 9600 Baud.
See the documentation for your Modbus devices for more information on
the bit rates they support.
Mode Select the transmission mode used by the SmartServer for communicating
with Modbus devices. You have the following two choices:

RTU. Data is sent as two 4-bit, hexadecimal characters. RTU mode
provides a higher throughput than ASCII mode at equivalent baud
rates.
This is the default.

ASCII. Data is sent as two ASCII characters. ASCII mode provides
increased flexibility in regards to the timing sequence, as there can be
up to a 1-second interval between character transmissions without
communication errors occurring.
Data Bits Select the data bit size for messages sent over the Modbus network. A
data bit is a group of 5 to 8 bits that represents a single character of data
for transmission over the network. Data bits are preceded by a start bit,
and they are followed by an optional parity bit and one or more stop bits.
The default value is 8 bits.
Parity Select the parity bit size for messages sent over the Modbus network. A
parity bit is an extra bit used to check for errors in groups of data bits
transferred between devices. The default parity size is none.
Stop Bits Select the number of stop bits used on the Modbus network. The default
value is 1 stop bit.
4. Click Submit.
Creating and Configuring Modbus Devices
You can add Modbus devices to the local SmartServer network. Because of of the many variations in
Modbus deviceas, conduct compatibility testing before using the SmartServer with Modbus devices in
your production systems. Modbus support with the SmartServer has been tested with the following
devices:

ABB ACH550*

Berg UBN 3060*

Berg UBN 315