RealTime field communications

RealTime field communications often use dial-out or dial-in modems. The primary difference is that dial-in modems are used by remote field devices while dial-out modems are used by the host.

A dial-in modem is used by the remote field device to communicate with the project site (host) regarding alarm conditions.

A dial-out modem is used by the host to communicate with remote field devices. It can be used for:

• Scheduled infrequent polling of remotes

• Polling of the remotes on demand (in response to a command from a Controller)

• An alternate communication line for polling the remotes

• A primary communication line or dedicated dial-out line (long-term connection)