iC-RC1000 acts as an independent monitoring device for industrial safety controllers and drive systems in the evaluation of sine encoders for SIL applications.
In this function the IC checks that four analog signal lines have the correct DC voltage range (DC range: 30 to 80 % from VCC1 or VCC2) and that two respective paired lines have the correct differential 1 Vpp signal amplitude in real time (amplitude range: 200 to 300 mV). Signals with twice this amplitude (400 to 600 mV) referenced to ground can also be monitored; here, the negative input must be kept within the permissible DC range (e.g. VCC/2).
iC-RC1000 has intrinsic safety, enabling single errors to be securely identiﬁed through redundancy; independently of one another, two different diagnostic channels monitor the input signals, outputting separate messages. The Signal OK and the Signal error statuses are complementary to one another if the chip is functioning correctly.
Each diagnostic channel has signal comparators windows have a different design depending on the for DC and square sum monitoring; the monitoring good/bad diagnosis.
So that the external controller can safely detect an interrupt, the status times are extended to at least 10 ms by retriggerable monoﬂops. After power on iC RC1000 starts in Signal error status, setting the Signal OK status at the earliest after the monoﬂop period has elapsed. The status outputs are conﬁgured as push-pull drivers so that optocouplers can be directly connected up to the device (10 mA low side, 4 mA high side).