Applies To:
  • CitectSCADA 3.xx, 4.xx, 5.xx

I have a device that uses the Modbus protocol on a RS-485 serial link. I also have a device called a Lantronix Serial Server to act as a gateway between the ethernet and serial media. How do I setup a Lantronix Ethernet Server with Citect? 

1. You can use Modbus over TCP/IP (see Q2449 for background)


Boards form:
Board Name: TCPIPBoard
Board Type: TCPIP
Address: 0
Ports Form:
Port Name: ModBusTCPIP_Port
Port Number: 1
Board Name: TCPIPBoard
Special Options: -I192.168.1.248 -P3001 -T
I/O Devices form: the only thing different here from a direct serial connection is the port definition
Name: IODev_RemPort
Number: 1
Address: 1
Protocol: MODBUS
Port Name: ModBusTCPIP_Port


2. You need to set the IP address of the Lantronix Server. To do this connect to the console port with a PC running Hyper Terminal or equivalent and perform the following (the default password is 'system'):

Lantronix MSS485 Version V3.5/5(980529)

Type HELP at the 'Local_2> ' prompt for assistance.

Username> Citect

Local_2> set privileged


Local_2>> change bootp disable

Local_2>> change rarp disable

Local_2>> change ipaddress

Local_2>> change gateway

Local_2>> change domain ""

Local_2>> change nameserver

Local_2>> change session limit 1

Local_2>> change speed 19200

Local_2>> change charsize 8

Local_2>> change stopbits 1

Local_2>> change parity none


3. Once the IP address is set you can Telnet to the Lantronix Server to change / view parameters eg:

Lantronix MSS485 Version V3.5/5(980529)

Type HELP at the 'Local_3> ' prompt for assistance.

Username> Citect

Local_3> set privileged


Local_3>> show port

Port 1: Username: Physical Port 1 (Idle)

Char Size/Stop Bits: 8/1 Baud Rate: 9600

Flow Ctrl: None Session Limit: 1

Parity: Even Modem Control: None

Access: Remote Break Ctrl: Local

Local Switch: None Start Character: None

Forward: None Backward: None

Port name: Port_1 Terminal Type: None

Preferred Service:

Characteristics: Verify Telnet Pad

Sessions: 0 Current Session: None

Input/Output Flow Ctrl: N/N DSR/DTR/CTS/RTS/CD: N/Y/Y/Y/Y

Seconds Since Zeroed: 41 Framing Errors: 0

Accesses Local/Rem: 0/0 Parity Errors: 0

Flow Control Violations: 0 Overrun Errors: 0

Bytes Input: 0 Bytes Output: 103

Input Flow On/Off: 0/ 0 Output Flow On/Off: 0/ 0

Local_3>> show server

MSS485 Version V3.5/5(980529) Uptime: 0:21:00

Hardware Addr: 00-80-a3-1d-04-ae Name/Nodenum: MSS_1D04AE/ 0

Ident String: Micro Serial Server

Inactive Timer (min): 30 Serial Delay (msec): 30

Password Limit: 3 Session Limit: 1

Queue Limit: 32 Node/Host Limits: 50/20

LAT Circuit Timer (msec): 80 Keepalive Timer (sec): 20

Multicast Timer (sec): 30 Retrans Limit: 10

TCP/IP Address: Subnet Mask:

Nameserver: Backup Nameserver: (undefined)

TCP/IP Gateway: Backup Gateway:

Domain Name: Daytime Queries: Enabled

TCP Keepalives: Enabled

DHCP Server: None Lease Time: 0:00

Load Address: aa-00-04-00-02-10 Prompt: Local_%n%P>


Incoming Logins: Telnet (No Passwords Required)

LAT Groups: 0