Industrialised modems keep PLCs in touch

Mitsubishi Electric reckons its new industrialised PSTN intelligent modems take away most of the difficulties associated with modem applications.

Mitsubishi Electric reckons its new industrialised PSTN intelligent modems take away most of the difficulties associated with modem applications, and have a host of special features to maximise their usage in the automation environment.

These new plug-and-play modems come in three styles to suit most applications.

The first is the A2S-Modem, which is specifically designed to sit as a module in Mitsubishi Electric's highly popular AnS PLC system.

The second version DIN-Modem-2 is for connection to other Mitsubishi or third-party manufacturers equipment, and is DIN-rail mounted for installation in cabinets.

The third version is a desktop version called Desk-Modem-2.

The modems come preconfigured to connect to any Mitsubishi PLC or HMI system without any settings being made.

The modems are also totally configurable to talk with any other manufacturer's product that has an active serial communications ability, as the modems are software controlled, rather than hardware controlled unlike most other industrial modems.

The new modems come with a host of value added features that differentiate them and give greater performance over conventional modems, such as a wide area telemetry (WAT) function, which when connected to a PLC allows it to act as a telemetry outstation.

The PLC can then communicate directly to another out station to transmit status or exchange data.

Because the outstations node number is a telephone number, it means there is virtually no limit to the amount of outstations that can be communicating on one network.

Remote maintenance and diagnostics are now made extremely simple and cost effective by the new modems' automatic simultaneous voice and data (ASVD) transmission capability.

By plugging normal telephone headsets or handsets into the modems, a user can transmit data to a PLC and at the same time talk to the machine operator on the same telephone line.

This single telephone cable communications ability drastically reduces the cost of installations and maintenance engineering time.

This modem function enables the user to talk to the machine operator actually at their machine for instant help on diagnostics, shortening potential downtime, and providing new dimensions to the services that can be provided to machine customers.

The modems also have an automatic dial on demand (DOD) facility, which allows the user to configure the modem to dial preprogrammed numbers when commanded to do so by the PLC application program.

This feature is extremely useful in alarm circumstances as well as for timed information transmissions and other dial requests.

The SMS messaging capability allows the modems to send SMS text messages to mobile phones, pagers or other SMS compatible equipment via the PSTN network.

This unique feature allows the modems to send a pre configured text message of up to 48 characters long message, for example to a maintenance engineer, should any errors occur on the system, even without the connected PLC being powered up.

Security is always paramount when connecting automation to a public phone system.

The new modems have two levels of security access coding, protecting the connected equipment from unauthorised connection or communication.

The modems when connected to a PLC allow a user to remotely programme the PLC online, allowing real-time remote monitoring and servicing to be performed.

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