CROME Rackable system has the same functionalies as CROME Bulk version. The main difference is in the fact that the ionization chambers are not physically attached to the electronics. Due to radiation levels, we use plastic chambres that are connected to the electronics through long SPA6 cables that have been especially design to transport some femto-ampers over long distances (up to km)
The form factor of the CROME rackable electronic is not the same as the CROME Bulk. As the name can suggest, the reachable version is meant to be used into a custom NIM chassis that has been designed by CROME team. Although, there is no need to use alarm units in this configuration, CROME rackable version has the option to connect such devices.
CROME delivers output signals and acquires input signals to condition its output functions. These signals are transmitted via connected cables. Output signals from multiple CROME units need to be aggregated with logical functions to provide summary signals to alarm repeaters or for interlocks. Input signals from external systems must be duplicated and distributed to be available to multiple CROME units.
To date, for historical reasons (number of managed signal, connection types, configurations, technologies available at the time of installation) various types of interlock junction boxes with diverse functionalities are installed. Only few are compatible with the CERN interlock system (CIBU) and none of them was design to be SIL2 compliant and is suitable for new installation. For that reasons, CROME System has gained an aggregator in order to emulate centralized functionalities that were implemented in ARCON. A visualization of the general status of access/interlock system is remotely possible.
The developed CJB (CROME Junction Box) is similar in function to the current PJI. It aggregates CROME output signals and to distribute Input signals.