Modem for Telephone Line, Wireless or Radio Communication and Data Acquisition

Part No.: DAS-PMB-PCC-012 *** This part has been discontinued, effective 2/2/07.

General Description:
The modem is a small, ruggedized programmable communication controller designed to facilitate communication over telephone lines, or radio link. Once installed, just dial up the modem from a PC or computer being used for the data acquisition and you are then ready to communicate with the field device. It is "self - testing" on power up and includes diagnostics and initialization which can be monitored with 8 LED status indicators on the side of the module. Our modems include a built-in wide ranging power supply with an input of 85 to 268 VAC or 65 to 380 VDC. All modem electronics are housed in a rugged, powder coated steel enclosure designed to withstand the rigorous of hostile environments. Wiring is accomplished by means of a pluggable quick connect/disconnect connector. The modem, as a smart communications controller, makes it possible to communicate with field devices virtually anywhere in the world where there is access to telephone lines. The application possibilities are almost unlimited. And with wireless communications becoming more of a factor, Axiomatic can now also offer communication via cellular telephone or radio. This will provide added flexibility where phone lines are not available.

Application:
A major electrical utility needed a method to interface intelligent meters for revenue purposes from the field to the billing office. The problem they encountered was trying to achieve consistent, reliable communications interfacing with RS-232 and RS-485 ports. Standard "off the shelf" modems could not offer this.
Tested and verified as compatible and reliable with Power Measurement's 3000 or 7000 meters and Schlumberger's Q 1000 meters, the modem is available for purchase directly from Axiomatic Technologies, a leading industrial control and electronics company.
With an installed base of several hundred units in western Canada, this modem has improved data transmission reliability with cellular communications as compared to other modems.
This remotely configurable unit will eliminate the need for RS232C/485 communications converter and DC power supply since these features are incorporated within Axiomatic modem. Available with a wide ranging operating voltage of 85 to 268 VAC or 65 to 380 VDC for ease of application.

Configuration:
Operation is configured locally or remotely via the modem/radio connection using a menu and prompts. Using the menu the communications port and the state of the diagnostics can be configured. The configuration menu will also indicate the state of the system's non-volatile memory. If the non-volatile memory should become corrupt or otherwise unavailable, the modem will default to an operational state in order to allow local or remote re-configuration. The modem will invisibly support most asynchronous serial communications formats. It includes support for hardware or software flow control and can support baud rate conversion. The modem onboard processor can also be configured for operation as a protocol converter. Customer specific protocols can be provided upon request. Axiomatic can factory configure the modem to simplify operation.

System Connection:
The Axiomatic modem allows field devices to be connected via RS-232 or RS-485. Whereas the typical distance between field devices and an RS-232 is approximately 50 ft., this can be significantly extended using the fully isolated RS-485. At low baud rates using an unshielded twisted pair cable, distances up to several kilometers can be achieved, depending on ambient noise.
The system is contained within a rectangular metal box 8 inches wide by 6.2 inches deep and 3 inches thick. It stand on four plastic feet and has four bulk head mounting slots.
Connection to the box is via a 16 pin pluggable screw terminal connector mounted on the 3 inch high side of the box. There are 8 status indicator lights above this connector.

RS232 Interface:This connection is not galvanically isolated from the unit. It should be limited to short distances (under 50 feet) and not be exposed to significant transients or ground shifts. This interface contains no additional filtering or hysteresis compensation, but is series current limited and protected by MOVs.

RS485 Interface: This interface connection is fully isolated and is good for a considerable distance. It is specified to support up to 32 drops. The greatest length will be achieved at low baud rates, using Point to Point, critically terminated, high quality (consistent characteristic impedance) unshielded twisted pair data cable. Using this method and depending on the amount of ambient noise, reliable operation may be achieved for several kilometers. As ambient noise increases or additional nodes are connected to the bus, the maximum length of the bus needs to be decreased. A nominal system consisting of 6 devices on the bus, with termination within 90% of critical tolerances and utilizing a decent data cable, should work reliably for 1 kilometer. In noisy environments it is recommended that shielded cable be utilized. The shield will however, attenuate the signal and reduce the maximum allowable length. Straight line bus topologies should be used exclusively if the system needs to work over a long distance.

Modem Status Indications:
The system is designed with eight external LEDs to aid in installation and debugging. These include : 3 power supply LEDs; RS232 and RS485 LEDs; an ON-LINE LED; and two status LEDs.
Modem Power Supply LED Indicator: Indicates the state of the power supply.
RS232 and RS485 LEDs: Will turn on each time a good character is received by a communications port. A good character means that it is free from all communications errors. Any characters received with errors are discarded by the communications processor.
ON-LINE LED: Indicates state of the connection. A short blink every second indicates online, a longer blink or solid on indicates characters received or transmitted through the modem or radio link.
System Status A, System Status B: Indicate the progress or state of the control program. When the system is first powered on it will perform a self diagnostic test. The progress of this test will be indicated by the LEDs.

Technical Specification:

Supply Voltage Requirements:

* Optional 12 V DC or 18 to 60 V DC for battery powered systems. Heavy gauge low inductance, earth connection required for trouble free and safe installation.

Operating Conditions:

Packaging: Size: 8.0" x 6.2" x 3.0" (W x H x D )

Ordering part number: DAS-PMB-PCC-012
(Contact manufacturer for other power supply input versions.)

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