Delta RMC151 - Manual (Page 450)

RMC70/150 and RMCTools User Manual
Every Ethernet device manufactured is required by the IEEE Standards Organization to have a
unique MAC address. This address is also called a LAN MAC address or Ethernet ID. This
address is given in the form of six hexadecimal bytes, which can be displayed in several
formats: run together (e.g. 0050A0984001), separated by hyphens (e.g. 00-50-A0-98-40-01),
or separated by spaces (e.g. 00 50 A0 98 40 01). However, all formats are equivalent.
Network administrators may require this value when tracking network problems or configuring
BOOTP or DHCP protocols. All Ethernet devices manufactured by Delta Computer Systems,
Inc. begin with "00 50 A0".
The MAC address on the RMC75E is printed on the label on the side of the RMC75E CPU
module. The MAC address on the RMC150E is printed on the label on the front of the CPU
module.
6.8.10. Supported Protocols
6.8.10.1. Modbus/TCP
This topic describes the RMC support of the Modbus/TCP Ethernet protocol. Whether you are
using it to communicate with the RMC from a PLC or from a custom application, this
information may be useful.
The Modicon Modbus/TCP protocol is one of the simplest protocols and has an open standard.
This means the protocol specification is publicly available. See the Modicon Modbus/TCP web
site at http://www.modbus.org for complete details on the protocol.
Supported Modbus function codes:
• Read Multiple Registers (FC 3)
• Read Input Registers (FC 4)
• Write Single Register (FC 6)
• Get Diagnostics (FC 8)
• Write Multiple Registers (FC 16)
• Read/Write Registers (FC 23)
Addressing and Data Format
See the Modbus Addressing topic.
Implementation Notes
While the Modicon Modbus/TCP web site has documentation and sample code for its
Modbus/TCP protocol, it is worth pointing out a few specifics on communicating with the
RMC over Modbus/TCP. This section neither replaces nor modifies the Modbus/TCP
specification, but clarifies key points and defines the RMC's function support.
• To create a connection with the RMC over Modbus/TCP, open a client socket with the
RMC on TCP port 502. The RMC will only respond to Modbus/TCP requests on this
port. Other ports are reserved or used by other protocols.
• The Unit Identifier (Slave Address) field in the Modbus/TCP is only used by routing
devices. Since the Slave Address is not used by the RMC, it should be set to zero (0)
in requests to the RMC.
• Typically, only functions 3 and 16 are used. Function 23 can be used to improve
performance by doing a read and write in a single function. FC 4 and 8 were included
for compatibility with existing Modbus/TCP masters, but otherwise add no value to the
RMC.
430 Delta Computer Systems, Inc.