Yaskawa JAPMC-MC2303-E - Manual (Page 17)

1.4 FAQ on FL-net
1-4
1.4 FAQ on FL-net
The following gives a list of frequently asked questions and answers.
Question Answer
1 What is Ethernet?
Ethernet refers to a cable type specification, and is available with local area networks
(LAN). Ethernet enables data transfer between computers at a baud rate from 10 Mbps
to 100 Mbps.
Presently, the prevailing Ethernet cable for office automation is a 100-Mbp twisted pair
cable (UTP). Ethernet allows communication through the use of multi-vendor software
protocols.
2 What is FL-net?
FL-net refers to a network capable of interconnecting FA controllers such as program-
mable controllers (PLC) and computer numeric control (CNC) equipment so as to trans-
fer control data at high speed between controllers.
Cables are identical to those employed for Ethernet.
3
What is the difference between
FL-net and Ethernet?
Ethernet is used to connect controllers to the host computer or PC so that production
directions can be given or performance information can be obtained for informational or
control purposes. On the other hand, FL-net is used to connect controllers for high-
speed control data transfer.
When one controller is used for both an FL-net to connect controllers and an Ethernet to
connect controllers to the host devices, care should be taken for correct cable connec-
tion.
4
How should we use the FN-net
unit?
The FL-net unit should be installed in FA controllers such as a programmable controller
(PLC) and computer numeric control (CNC) equipment so that data transfer can take
place cyclically between the controllers as long as link assignments for station numbers
(node numbers) and common memory (also called “link register”) are simply made in
the same manner as for regular PLC CPU link units. In this case, no special communi-
cation program is required for PLC, etc. In addition, when PLC memory contents or
communication parameters are read or written from PC, no special communication pro-
gram is required for PLC, etc.
However, note that each controller should be provided with a communication program
when data transfer is attempted between controllers through message transmission.
5
What is a protocol?
What protocol is supported by
FL-net? Protocol refers to a set of rules required for communication.
FL-net employs an FL-net-dedicated FA link protocol that lies in the UDP/IP or upper
layers.
6
Does FL-net allow general PC
connections?
The FL-net units to be installed in FA controllers such as a programmable controller
(PLC) and computer numeric control (CNC) equipment are intelligent units with pro-
cessors on their boards. Because PC Ethernet cards are non-intelligent cards called
“dumb cards,” it is generally recommended to use FL-net boards according to PC per-
formance and usage.
7 What is topology?
A networking topology refers to a network wiring method. Though star (tree), bus, and
ring topologies are available as main topologies, they can be understood more easily
from a viewpoint of logical wiring rather than physical wiring.
A star topology is used for 10BASE-T/100BASE-TX in FL-net. On the other hand, a
bus topology is used for 10BASE5 in FL-net.
8
What types of network cables
are available? How long are
the cables and how many
nodes can be connected to
them?
The following summarizes the standards, characteristics, and restrictions of the most
popular Ethernet cables.
• 10BASE-T/100BASE-TX: Twisted pair cable (UTP), maximum transmission dis-
tance per segment: 100 m (500 m), maximum number of connectable nodes per seg-
ment: 254
• 10BASE5: Thick coaxial cable (yellow cable), maximum transmission distance per
segment: 500 m (2,500 m), maximum number of connectable nodes per segment: 100
(254)
• 10BASE-FL/100BASE-FX: Optical fiber cable, maximum transmission distance per
segment: 2,000 m, maximum number of connectable nodes per segment: 254
∗ Values in ( ) assume the use of repeaters.
9
When a system uses FL-net,
does it need a special Ether-
net?
No. To build an FL-net system, Ethernet is used (which is formally compliant with
IEEE802.3). Special specifications are not required.
10
How should we make FL-net
connections?
Different types of Ethernet media can be interconnected with Ethernet cables through
repeaters, media conversion adaptors, etc. These products can be purchased from many
vendors.