Delta RMC101 User Manual
Page 313
Ethernet 5.2
Communications
5-63
Each protocol is briefly described below:
• ARP (Address Resolution Protocol)
Ethernet packets can either be broadcast (received by all devices on the network) or sent to a
single MAC address. However, applications generally address computers by IP address rather
than MAC address. Therefore, this protocol is used to determine the MAC address of the
computer owning a given IP address.
• BOOTP (BOOTstrap Protocol)
This protocol is used to allow a central database to be maintained with all IP addresses on a
network. This single computer is the BOOTP server. When a BOOTP client (such as the RMC, if
configured to use BOOTP) starts up, it broadcasts asking a BOOTP server to tell it what its IP
address should be. The BOOTP server looks up the MAC address of the BOOTP client in a
database and sends a reply with the corresponding IP address.
• CAMP (Common ASCII Message Protocol)
This is an open protocol developed by Control Technology, Inc. who manufacturers the CTI 2572
which allows the Siemens Simatic TI505 controller to communicate via Ethernet. Information is
available on this protocol from CTI's web-site: http://www.controltechnology.com.
• CSP (Client/Server Protocol)
This is a proprietary protocol developed by Allen-Bradley, Inc. Variants of this are used on Allen-
Bradley's SLC 5/05 and PLC-5 controllers. This protocol is also used by the Allen-Bradley's
SoftLogix 5 and RSLinx and SoftPLC Corporation's SoftPLC. Allen-Bradley does not publish the
specifications for this protocol.
• DHCP (Dynamic Host Configuration Protocol)
This protocol is an enhanced version of BOOTP. However, for industrial applications, the
enhancements (lease times and dynamic assignment of IP addresses) are generally not usable.
The RMC supports both BOOTP and DHCP so that the user may use either type of server.
• Ethernet II
This is the most common framing layer protocol used by Ethernet devices. Other alternatives
include IEEE 802.3 SNAP, IEEE 802.5 (Token Ring), and IEEE 802.4 (Token Bus). The RMC
only supports Ethernet II framing, and therefore will not work on networks using any of the other
framing types. All PLCs currently support Ethernet II framing although the Modicon Quantum
allows selecting either Ethernet II (the default) or IEEE 802.3 SNAP.
• EtherNet/IP
This is an open application protocol, originally developed by Allen-Bradley, Inc. as EPIC, but now
maintained and distributed by ControlNet International (http://www.controlnet.org) and ODVA
(http://www.odva.org). The specification and source code are available through
http://www.ethernet-ip.org. This protocol is an Ethernet-adaptation of the Control Information
Protocol (CIP) in the same way that DeviceNet is a CAN adaptation of CIP and ControlNet is a
CTDMA-adaptation of CIP. EtherNet/IP is used by the Allen Bradley ControlLogix's Ethernet
modules (1756-ENET and 1756-ENBT).
• FINS