Installation guide

Glossary

112

890USE17100 September 2003

repeater An interconnection device that extends the permissible length of a bus.

reverse polarity

protection

Use of a diode in a circuit to protect against damage and unintended operation in the

event that the polarity of the applied power is accidentally reversed.

rms root mean square. The effective value of an alternating current, corresponding to the

DC value that produces the same heating effect. The rms value is computed as the

square root of the average of the squares of the instantaneous amplitude for one

complete cycle. For a sine wave, the rms value is 0.707 times the peak value.

role name A customer-driven, unique logical personal identifier for an Ethernet Modbus TCP/

IP NIM. A role name is created either as a combination of a numeric rotary switch

setting and the STB NIP 2212 part number or by modifying text on the Configure

Role Name web page. After the STB NIP 2212 is configured with a valid role name,

the DHCP server will use it to identify the island at power up.

RTD resistive temperature detect. An RTD device is a temperature transducer composed

of conductive wire elements typically made of platinum, nickel, copper, or nickel-

iron. An RTD device provides a variable resistance across a specified temperature

range.

Rx reception. For example, in a CAN-based network, a PDO is described as an RxPDO

of the device that receives it.

SAP service access point. The point at which the services of one communications layer,

as defined by the ISO OSI reference model, is made available to the next layer.

SCADA supervisory control and data acquisition. Typically accomplished in industrial

settings by means of microcomputers.

SDO service data object. In CAN-based networks, SDO messages are used by the

fieldbus master to access (read/write) the object directories of network nodes.

segment A group of interconnected I/O and power modules on an island bus. An island must

have at least one segment and may have as many as seven segments. The first

(leftmost) module in a segment needs to provide logic power and island bus

communications to the I/O modules on its right. In the primary segment, that function

is filled by a NIM. In an extension segment, that function is filled by an

STB XBE 1200 BOS module.