The difference between the two and four wire connection modes of smoke alarms
Two line smoke sense is divided into bus coding type and non coding current mode, power line and signal line and two one;The four wire smoke sense is the type of relay switch signal, the signal line and the power line are separated.
No matter he is four wire or two wire, as long as you know what you choose the sensor, if you need PLC to provide power for the sensor, which is the two wire, if the sensor itself has power to PLC is only a standard signal, that is the four line, line like are the same, just not the same type of sensor
1. two line of smoke only 2 lines and host bus terminal or signal terminal directly connected to a plurality of mutually parallel smoke, if the smoke is non line 2, connected to a terminal resistor in the end of a smoke.2. four line smoke DC12v or DC24v power supply required by the security or the corresponding host can provide equipment, can also be provided separately; signal end is 2 separate lines, normally open or close connection is selected according to the equipment need, directly connected to the receiving end can signal equipment.
