According to the B30 product manual order code specifications, the unit is horizontal unit with the following general product breakdown: B30-***-***-F**-H**-L**-N**-S**-U**-W/X**. The CPU is of the K order code. This affords the CPU with a RS485 and a multi-mode ST redundant 100Base-FX communication ability. There are actually three digital I/O modules contained in this particular B30 unit. The three digital I/O modules are a 67 (H67) order specification and a 6D (N6D) order specification and a 4A option (U4A). The 67 option includes 8 Form-A outputs with a lack of circuit or voltage monitoring options. The 6D digital I/O module has 16 digital inputs. Finally the 4A option indicates four solid state MOSFET outputs that also lack circuit and voltage outputs. With a variety of order options the B30 bus differential relay can be tailored to a precise application for use. Typically input elements will obtain analog or digital field signals which are converted by the UR to logical signals that can be used by the relay. Then the logic signals generated can be switched to digital or analog signals to sent to devices in the field.