Server User Manual
    Server Properties Configuration 
Manual Documentation Number: ESP901-902_4105m  Chapter 5  35 
B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104 – www.bb-elec.com 
B&B Electronics Ltd – Westlink Commercial Pk – Oranmore, Galway, Ireland – Ph +353 91-792444 – Fax +353 91-792445 – www.bb-europe.com 
Flow Control 
The Flow Control setting must match the requirements of the serial 
device connected. 
N
N
o
o
t
t
e
e
:
:
 Select None when setting the port as RS-485 or 4-wire RS-422. 
TCP/UDP Protocol 
Select  TCP (Transmission Control Protocol) or UDP (User Datagram 
Protocol) protocol. If the application does not require a UDP 
connection, select TCP. TCP guarantees reliable communication with 
error checking whereas UDP provides faster transmission. 
UDP Mode 
When UDP mode is chosen the Serial timeout,  TCP alive timeout, 
Connection mode,  Connection at,  Max connection and 
Remote IP address fields are replaced with the following 
four fields: 
Destination IP address range, Port number and 
Source IP address range. In this mode the server can be 
configured to broadcast data to and receive data from multiple 
IP addresses. Four IP address range fields are provided. 
Figure 32.  The Server UDP Configuration Screen 
Serial Timeout 
Default for the Timeout property is 0, or no timeout. Setting Timeout 
to any value between 1 and 65535 seconds activates it. If 
Timeout is 
set to 5 seconds and the Serial Server is configured as a Server, the 
Client makes a connection and communications starts. If 
Server Properties Configuration 
36  Chapter 5  Manual Documentation Number: ESP901-902_4105m 
B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104 – www.bb-elec.com 
B&B Electronics Ltd – Westlink Commercial Pk – Oranmore, Galway, Ireland – Ph +353 91-792444 – Fax +353 91-792445 – www.bb-europe.com 
communications are ideal for 5 seconds the Serial Server will reset and 
make itself available for another client connection.  
TCP Alive Timeout 
The Serial Server monitors TCP activity. If TCP activity stops for the 
length of time specified in this field the connection will be closed. This 
field can be set to any value between 0 and 255 minutes. If zero, or no 
value, is entered into this field the server will not disconnect. 
Connection Mode 
The Connection Mode field has three options: Server, Client and 
Client (no heartbeat). When  Client or Client (no heartbeat) is 
selected  the Connection at field automatically becomes active 
(allowing the user to select 
Power up or Data Arrival). 
•  When using the 
Virtual COM Port feature, select Server. 
•  When using a 
TCP or UDP Socket program, select Server. 
•  When using 
Paired Mode communication between two serial 
servers set up one as a Client and the other as a Server. 
•  When connecting to a server that does not support 
Heartbeat, 
select 
Client (no Heartbeat). 
Delimiter HEX 1 and Delimiter HEX 2 
These fields allow the user to enter two ASCII characters (in hex 
format) that delimit the beginning and end of a message. When a 
message with both these delimiters is received at the serial port, the 
data contained in the serial buffer is placed in an Ethernet packet and 
sent out the Ethernet port. If only Delimiter 1 is set (Delimiter 2 is zero 
or blank), upon receiving Delimiter 1 the ESP901/902 will put all the 
data in the serial buffer in an Ethernet packet and send it out the 
Ethernet port. If serial data greater than 1 kilobyte is received it will 
automatically be placed in an Ethernet packet and sent out the Ethernet 
port . 
Force Transmit 
This field allows the user to set a maximum time limit between 
transmissions of data. The value set in this field multiplied by 100 ms 
determines the Force Transmit time. When the elapsed time reaches the 
time configured in this field, the TCP/IP protocol will pack the data 
currently in the serial buffer into a packet and send it out the Ethernet 
port. 










