Yaskawa LEGEND-MC - Manual (Page 55)

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LEGEND-MC User’s Manual
Communicating with Multiple Devices
The LEGEND-MC is capable of supporting multiple masters and slaves. The masters may be multiple
PC's that send commands to the controller. The slaves are typically peripheral I/O devices that receive
commands from the controller.
An Ethernet handle is a communication resource within a device. The LEGEND-MC can have a
maximum of 8 Ethernet handles open at any time. When using TCP/IP, each master or slave uses an
individual Ethernet handle. In UDP/IP, one handle may be used for all the masters, but each slave uses
one. (Pings and ARP's do not occupy handles.) If all 16 handles are in use and a 17
th
master tries to
connect, it will be sent a "reset packet" that generates the appropriate error in its native application.
Multicasting
A multicast is only used in UDP/IP and is similar to a broadcast (everyone on the network gets the
information) but specific to a group. As such, all devices within a specified group will receive
information sent in a multicast. The many multicast groups on a network are differentiated by their
multicast IP address. To communicate with all devices in a specific multicast group, information can be
sent to the multicast IP address rather than to each device IP address. All LEGEND-MC controllers
belong to a default multicast address of 239.255.19.56. The controller's multicast IP address can be
changed by using the IA> u command.
Using Third Party Software
Yaskawa supports ARP, BOOT-P, and Ping, which are utilities for establishing Ethernet connections.
ARP is an application that determines the MAC address of a device at a specific IP address. BOOT-P is
an application that determines which devices on the network do not have an IP address and assigns the IP
address you have chosen to it. Ping is used to check the communication between the device at a specific
IP address and the host computer.
The LEGEND-MC can communicate with a host computer through any application that can send TCP/IP
or UDP/IP packets. A good example of this is Telnet, a utility that comes with most Windows systems.
NOTE: A command sent over an Ethernet Telnet session must reside in one packet. This means that a
Telnet emulator must not send a command such as MG_TPX<CR> until the carriage return is present; i.e.,
do not send one character at a time as the user enters them.