The Loop Interface LIF601-2 supports one loop with bi-directional communication in Fire Detection Control Panels Series BC600. The protocol for the loop communication is set through the parameterization of the control panel and it determines the maximum number of detectors and modules that can be connected to the loop: 240 physical address points (detectors or modules) with Labor Strauss protocol; 318 physical address points (159 detectors and 159 modules) with System Sensor protocol; 252 physical address points (detectors or modules) with Apollo protocol. The loop allows connection of manual call points, automatic detectors, input and output modules, RF gateways and signalling devices in loop technology. Usually, the loop is wired as ring with unshielded 2-wire cables; if necessary, branch lines can also be connected to the ring without additional devices. If shielded cables are to be used, both shields can be connected directly to the loop interface, which makes wiring much easier and ensures optimum protection against external EMC effects. In addition, the continuity of the shield can be monitored by the LIF601-2, a further measure to ensure error-free communication on the loop. Each loop can be divided into a maximum of 200 detector zones. Thanks to the high maximum output current of 600 mA, a large number of loop elements with higher current demand, such as sirens, can be used on the loop. In addition, the Loop Interface LIF601-2 is equipped with 8 freely parameterisable open-collector outputs for general control tasks. Extensive measuring functions for obtaining electrical characteristics, as well as analysis functions are integrated into the loop interface. On the LC display of the Fire Detection Control Panel Series BC600, the resistances of the positive and negative loop line, the present loop current, the loop voltage at all terminals and the relative frequency of faulty queries on the loop can be indicated. Furthermore, the way in which the loop resistance of both lines is determined by the LIF601-2 has been improved again, and therefore the present measured values are indicated even more exactly, and in addition, now the resistance can also be measured on Apollo loops. As a result, the quality of the loop cabling and of the data transmission can be evaluated in the course of commissioning or maintenance. In this way, for example, lines that are too long or poor wiring can be detected easily.