CHAPTER 5 - PXG200E THEORY OF OPERATIONEATON PXG200E User Manual • IM02603001E Rev 5, 11-May-2012 • Firmware Version 5.03:383522Access Control / Trusted Host ListThe PXG200E is designed to be integrated into a variety of systems;therefore, it is designed to allow SNMP, Modbus TCP and pass-throughfunctionality from any outside computer. While it is desirable to provideopen connectivity, it is prudent to restrict access to only those computersthat you trust or wish to have access. The PXG200E provides protocol“ports” on the Ethernet LAN for accessing:• Modbus TCP• SNMPv1 and SNMPv3(limited to device status only)• Encapsulated INCOM (used by PowerNet Software)There are two distinct parts to restricting access:1. Enabling/Disabling Access Control2. Entering the IP addresses or host names of trusted computers if youenable Access ControlRefer to Access Control on page 109 for configuration details.Modbus TCP Enable / Modbus TCP Write EnableModbus TCP is a very common and simple protocol for data access. Manycommercial products and freely available software will provide access to aModbus TCP server device. The PXG200E provides two additional controlsto help ensure the security of your system while still offering the option ofModbus TCP data access.The PXG200E provides the ability to turn off all access to Modbus TCP evenwhen you have allowed access to trusted hosts or open access to the otherprotocols listed in the previous section. Refer to Configuring Modbus TCPFeature on page 88 for details.A second control within the configuration will disable all writes via ModbusTCP.NOTICE: To ensure the security of your system, if you will not beusing Modbus TCP, leave (set) the Modbus TCP port to disabled. Ifyou will be reading data from Modbus TCP but not writing data,enable the port and disable Modbus TCP writes.
