... &combustible gas,temperature&pressure signal 3:4-20mA,Expandable channel security alarm systemFeature:1.Standard 4U tray-type metal construction,You may ... wire) Output signal 4~20mA Alarm setting low alarm, high alarm Alarm mode sound and light alarm Alarm sound ≥65dB Alarm output channel card independently has fault ... model AT0502AH/L,XP2000/L,XP3000/L 4U tray type security alarm system