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Register Rack Modem

The Niobrara RM14K Industrial Modem is a SY/MAX® register rack compatible modem which operates with dial-up public telephone lines (PSTN), leased lines (2-wire or 4-wire) or radios to provide a long distance serial communication link. It can communicate over an audio connection at rates up to 14,400 baud. It is equipped with a SY/MAX compatible RS-422 port with active RTS/CTS handshaking that can run at up to 19,200 baud in either 10- or 11-bit modes. The RM14K is compatible with the NR&D 2496X and 1296X modems; with proper configuration and software, the RM14K can also act as a standard 10-bit Hayes® compatible modem.

The SY/MAX capabilities of the RM14K make the module ideal for remote programming of SY/MAX processors, interconnecting of remote SY/NET® networks, and remote monitoring of devices such as PowerLogic® Circuit Monitors. In SY/MAX mode the RM14K can perform baud rate, data bit and checksum conversions and will respond to certain SY/MAX routes for configuration and control of the modem from the RS-422 port or the Line port. Leased line operation can be configured for point-to-point or multidrop mode (additional hardware, such as an EPE5, SPE4 or RNIM may be required for multidrop operation).

The Transparent mode allows non-SY/MAX communication over telephone lines, leased lines, and radios at up to 14.4K baud, in 10 or 11 bit modes. This mode is especially useful for communicating with the Micro-1™ or Model 50 processors or with PNIM, Modbus®, or ASCII devices. While in Transparent PSTN mode, the RM14K will respond to a set of Hayes AT commands for configuration and control of the modem from the RS-422 port.

The RM14K also provides a password security feature for preventing access by other PSTN users. When the password feature is enabled, a four digit DTMF code must be entered before the modem will initiate the answer sequence. The current password and a display of the last password entered are available to the PLC from the backplane in real time. This feature may also be used as a "Caller ID" system by assigning a unique password to be automatically dialed from each remote station.

Internally, the RM14K has non-volatile registers for storing modem setup parameters including the default phone number. These registers can be read and modified with RM14KSW software (included with the module), with SY/MAX read and write statements, or with Hayes® AT commands that many modem software packages can transmit. The RM14K also has rack addressable registers for modem control and monitoring. These registers can be read and modified from the PLC backplane or from the SY/MAX port using SY/MAX read and write statements.


Dimensions: Standard SY/MAX register module. 1.5" wide by 13" tall by 6.5" deep. Approximately four pounds net. Rugged welded steel enclosure with baked on finish. All connectors and indicators are front mounted except the SY/MAX bus card edge connector on the back.

Power Requirements: From SY/MAX bus. 5 volts, 0.8 A. For stand-alone applications, the RM14K may be powered by the NRK1 single slot power supply.

Connections: RJ11 jack for connection to telephone line
RJ11 jack for connection to handset or telephone
RJ11 jack for connection to 2-wire leased line or transmit or 4-wire leased line
RJ11 jack for connection to receive of 4-wire leased line
SY/MAX compatible RS-422 serial port with DB9 female connector
Phoenix COMBICON 4-position socket; voltage input for remote dial and relay contacts for push-to-talk radio control

Controls: All switches are momentary, double throw, self centering

SY/MAX or Hayes modeOriginate or Auto-Answer modeConnect or Hang-up

Modem: 300 to 14,400 bps; autoband selectable; dial-up, leased line, or radio compatible

RS-422 Port: SY/MAX compatible DB9 female connector with slide lock posts. SActive RTS/CTS handshake lines; 50 to 19,200 baud; odd, even, or no parity; 7 or 8 data bits; 1 or 2 stop bits.

Indicators: LED indicators for Power, Off Hook, Carrier Detect, Modem Transmit, Ring, and Auto-answer Enabled. LED transmit and receive indicators for SY/MAX port.

Protocols: SY/MAX 10- or 11-bit with CRC or BCC checksum; Hayes Smartmodem

Compatibility: Bell103, 212A; CCITT V.222, V.33, V.29, V.27bis
Niobrara, Racal-Vadic, UDS, and other modems; remote service from some PC internal modems

Setup Registers: Processor equivalent registers store the configuration of the unit. These registers maintained by AC power when present, by power supply when mounted in rack, and by internal capacitor for up to one week when removed from rack.


The RM14K is available as:

RM14K Rack Addressed Industrial Modem

Effective 01 October 1995 - Specifications subject to change without notice.