Dallas Semiconductor introduces sensor/actuator chip for closed-loop control from a PC; breaks the $1 per-node cost for distributed monitoring and control.

DALLAS--(BUSINESS WIRE)--Jan. 30, 1996--Dallas Semiconductor Corp. (NYSE:DS) Tuesday announced a sensor/actuator chip that can perform closed-loop control from a central PC.

The DS2407 Addressable Switch, an RS232 instrument, can activate a switch and can also monitor the presence or absence of voltage.

The two voltage sensors and two output transistors inside the DS2407 can be dynamically configured for operation as one sensor and one switch; two sensors; or two switches.

Said Michael Bolan, vice president of product development: "The chip was designed to exploit the computational, display and connectivity features of the PC. From the serial port of the PC, a twisted pair telephone wire can be routed up to 300 meters to multiple Addressable Switches.

"One signal plus ground provides the digital communication link as well as the power for the sensors/actuators."

Because the DS2407 draws its power from the communication line, no external power supply is required. Applications for the device include home, laboratory or factory automation, comfort control, burglar alarms, irrigation control, greenhouses and vending machines.

Driver software called TMEX (Touch Memory EXecutive) that is available from Dallas Semiconductor can feed sophisticated graphical user interfaces on the personal computer screen using software like LabView from National Instruments. Alternatively, the Addressable Switch can be connected to controllers on a FieldBus, DeviceNet or LonWorks, which are in turn connected to a PC.

Each DS2407 is individually addressable. That is, dozens of chips can be put on the same twisted pair wire and have a central PC turn them on and off individually. This is made possible by a guaranteed-unique serial number laser-etched in each chip that serves as a node address and an on-chip multidrop network controller. A 16-bit CRC generator guarantees that the data packets are communicated with integrity.

Said Bolan: "Everybody is looking for a better way to get information into a PC, and they are designing software-centered systems. Each DS2407 has a unique name. This allows the creation of self-organizing networks that feed a central database on a server. Primitive user interfaces with buttons, lights and gauges are giving way to the PC's graphical display."

The DS2407 provides a simple way to build a closed-loop system. The sensor responds to a stimulus and reports it to a PC. The PC makes a decision, and, based on that decision, the switch turns on or off to control a process.

Both of the DS2407's voltage sensors are designed to capture a one-shot, short pulse, such as one generated by a piezo-sensor or momentary contact closure -- and set a flag. TMEX driver software uses a conditional search command to singulate the devices that have flags set. The discovery rate from a PC COM port can be as high as 66 devices per second.

Said Bernhard Linke, product manager: "Piezo electric sensors such as the AMP LDTO-028K are an inexpensive way to convert mechanical motion to an electrical signal, but their signals are high impedance and not compatible with long cables and digital interfaces. The DS2407 is the missing link that captures the sensor's short pulse, latches it, and feeds it directly to the PC.

"The activity flag together with the speed of the conditional search provides a quick way to monitor for status changes in a burglar alarm system," he continued. "The exact location of the opened door or window is known before somebody can pass through the opening.

"Just a single pair of wires is needed to connect all sensors. There is no need to home run the wiring of each sensor in order to know its location."

The flexibility of the DS2407 is enhanced by 1,024 bits of user-programmable and write-protectable EPROM memory. This memory's data can be used to describe the physical location, identify the controlled equipment, calibrate the sensor, or reference the actuator to a specific sensor.

Said Linke: "Those 1,024 bits of extra memory can be used to physically label the location of the device -- Room 15 on the fifth floor. Not only does the PC know that an input was tripped; it also knows the exact name and location -- without referencing information in a central database -- because that information is stored in the chip.

"In this way, the PC can be changed without losing the description of the sensors' organization."

Because it is dual-channel, the DS2407 can drive bi-directional opto-isolators. One channel can light the LED while the other senses the response. This feature is used to build electrically safe opto-isolated interfaces to control high-power devices such as electric motors, heating or air conditioning systems.

The dual-channel DS2407 is available in either a six-pin TSOC surface-mount package or as a single-channel version in a TO-92 package. Available from stock, the dual-channel DS2407 Addressable Switch is priced at $1.96 each (less than $1.00 per input/output node) in quantities of 5,000. The DS9091K MicroLan Kit, which uses the DS2407 for a temperature control application, is available for $49.

Dallas Semiconductor designs, manufactures and markets CMOS chips and chip-based subsystems. In its 11-year history, the company has sold its products to more than 8,000 customers worldwide. These include original equipment manufacturers (OEMs) in instrumentation, factory automation, personal computers, office equipment, telecommunications, medical equipment and mainframe computers.

Chips and subsystems are sold through a direct sales force, distributors and manufacturers' representatives worldwide.

CONTACT: Dallas Semiconductor Corp., Dallas

Syd Coppersmith, 214/450-5349 (editors' contact)

Bernhard Linke, 214/450-0448, 214/450-0470 (fax)

(readers' contact)