BFM II supports up to 5 open TCP socked simultaneously.

If no accessible socket is meaning that all 5 socked are busy.

If some client program (SCADA) is trying each time open new TCP connection to port 502 very quickly all socket will be busy.

Typical reason of the issue is incorrect managing TCP connections.

If a client machine doesn't close correctly connection and no communication traffic via specific connection BFM II will close it when Connection Idle Connection will be expired.

Default 120 seconds. You can reduce it. Minimal is 30 seconds.

The SCADA should try use existing connection and only if it is not accessible try to open a new one.

Else, the SCADA should close connection each time when it finishing to receive response from BFM II.




Using telnet to monitor established connection to BFM II.

  • Supported in version 37.01.13 and higher.
    1. Activate Telnet Client in your computer.
    2. Run CMD
    3. Print telnet [IP address] and press Enter


Default password is '0'

Print 'enet' and press Enter

Print 'stat sock' and press Enter

Find established connections in the list of connections.


See example below:


Login password: *


BFM II Telnet commands


h or ?           - Display this text

i                - Firmware information

password         - Password setting

time             - Time/Date

com[port]        - Serial port settings

enet             - Ethernet network settings and info

mem              - Storage memory menu

service          - Enter service menu

diag             - Print device diagnostics

clrdiag          - Clear device diagnostics

restart          - Reset the device

scales           - Data scaling/limits settings



Ethernet Menu Commands


h        - Display this text

net      - Current network addresses

ip       - Network settings

stat [net|tcp|udp|ip|icmp|arp|snmp|dns|sock|history] - Network statistics

stop net - Shut the network down

run net  - Start the network

q        - Quit menu


ENET>stat sock

TCP socket statistics:

  TCP sock fhost           ports      opts     rxbytes  state:

  9124   23->xxxx 0x0100         1  ESTABLISHED

  92CC 1756->5001 0x0100         0  ESTABLISHED

  986C   23->   0 0x0102         0  LISTEN

  9704  502->   0 0x0106         0  LISTEN

  9434 2404->   0 0x0106         0  LISTEN

  959C xxxx->   0 0x0106         0  LISTEN

  9A8C   80->   0 0x0106         0  LISTEN