The CROME Junction Box (CJB) is a central equipement of CROME system. The CJB aggregate output signals coming from several CMPU (CROME Monitoring and Processing Units) devices as well as other systems (other Radiation monitors, access doors’ signals…) and combine them together in order to generate global interlock and alarm repeater signals.

The CJB has be designed to be modular by using separate I/O modules in order to be able to adapt to different physical and electrical signals. The base of the CJB is a 3U height Europa crate with a central backplane that permits the linking together of front and back modules through DIN41612 connectors.

From the back, eight I/O modules can be inserted. The width of each I/O module is 8TE (40.3mm). The goal of these I/O modules is to convert the signals coming from the external systems to logic signals and distribute them to and from the CPLDs through the backplane connexion. Each I/O module can interface up to 20 external I/O signals to the CPLDs, 10 for each CPLD. Each signal can be used as either an input or output signal, the configuration is made at the CPLD level. Different kinds of I/O modules are described below in the document. There is eight position available to insert I/O modules. The backplane connector is the same for each position; any type of I/O module can then be inserted at any position. A power entry panel permits to connect 230V AC and 24V DC power to the CJB and distribute it to the power modules through the backplane.

From the front, the two power supply modules as well as the processing module and the remote status module can be inserted. The two power supplies receive 230V AC and 24 DC inputs from the backplane and generate the 24V DC and 5V DC power rails that are distributed to all the other modules. The processing modules receive all the inputs and outputs and contain the two CPLDs that realize the logical processing. The remote status module gives access to the status of all I/Os remotely through an Ethernet connection.