## network components

This section describes the different components in : Servers, Sites, Devices, Dial-Out Modems, Connection Schedules, and System Log Events.

See "Setting Up Your Network in " on page 1 for information on adding these components to your network.

#### Servers

A server is a computer in the system that runs administrative software to control access to the network and its resources, such as metering devices.

#### Sites

A site is a group of devices in the system that share a common communications link. A site can be a direct site, a modem site, an Ethernet gateway site, or an OPC site.

##### Direct site

In a direct site, serial communications occur between a computer and one or more meters. The standards most commonly used on computers are RS-232 (for connecting one device) and RS-485 (for connecting a loop of up to 32 devices). When connecting to more than one serial device, use an RS-232 to RS-485 converter. Note that you should keep the number of devices on a daisy chain to a minimum to reduce the delay in real-time updates.

##### Modem site

In a modem site, communications occur between a remote modem (at the Modem Site) and a local modem (on the server).

Note

Remote sites that use radio modems or leased-line modems are configured as Direct (Serial) Sites, not as Modem Sites.

Modem sites can include traditional hardware modems (those that are configured and controlled by or WinModems (Windows modems). If multiple modems are set up in the modem site, selects the first available modem to establish communications (this is referred to as “modem pooling”).

##### Ethernet gateway site

An Ethernet gateway site (for example, EtherGate or Modbus gateway) consists of an RS-485 chain of devices that communicates with an Ethernet network via an Ethernet device. The Ethernet device acts as a gateway that transfers data between an Ethernet network and the devices connected to it via RS-485. The gateway device converts RS-232/RS-485 communications to and from Ethernet.

##### OPC site

An OPC site consists of an OPC client that communicates with OPC-compliant devices on the network.

#### Devices

A device is a meter or other component that communicates and gathers data, and is installed on a network.

##### Serial devices

Serial devices belong to direct sites, modem sites, or Ethernet gateway sites — they communicate through a modem, RS-232, RS-485, or Ethernet-to-Serial gateway connection. You must have the appropriate sites configured first before you can add serial devices.

##### Ethernet devices

Ethernet devices are those that are directly connected to the network via Ethernet. You can manually connect or disconnect your Ethernet device through the .

##### Logical devices

Logical devices are a collection of measurements from physical and VIP devices grouped into single sources for use in the system.

##### OPC devices

OPC devices represent physical devices to which the system is communicating through an OPC interface.

#### Dial-Out modems

A dial-out modem is one that a server computer uses to communicate with a remote modem at a modem site. The modem implemented can be a traditional hardware-based modem or it can be a software-based modem that uses the computer’s processor to emulate a traditional hardware-based modem.

When a modem site needs to establish communications, it selects a modem from the list of modems configured in the modem site. You can add hardware modems or WinModems to the modem list.

Note

A WinModem is a modem that is directly controlled by the computer’s operating system.

#### Connection schedules

Connection schedules are programmed routines for a server to regularly connect to and disconnect from sites (and their associated devices) and Ethernet devices. See "Configuring Connection Schedules" on page 1 for more information.

#### System Log Events

System Log Events lists events for the network. You can select what timeframe and components you want to view events for. See "System Log Events" on page 1 for more information.