The Models 8501 and 8502 from Calex Mfg. Co. Inc., Concord, CA, each contain 2 independent channels that accept a TTL or 24 V pulse signal and convert it to a 24 V pulse or TTL output. The Model 8501 is a 5 V to 24 V converter with a DC to 15 kHz input frequency and a floating optocoupler NPN transistor output. The 2 independent channels require 7 mA into 382 ohms to provide a 7 mA output into the 3 kilohm, 24 V typical PLC logic input. The Model 8502 is a 24 V to 5 V converter with a DC to 20 kHz input frequency range and 2 outputs, each capable of sinking a min. of 5 mA. Each input channel requires 7 mA into 2.5 kilohms to provide a 5 mA sinking output to TTL 5 V logic.
Calex Mfg. Co. Inc.