Справочник Пользователя для National Instruments RS422

For Zone 2 applications, install a protection 

device between the RS485/RS422 signal cables and the 
NI 9871 RJ-50 jacks (ports 1– 4). The device must 
prevent the RS485/RS422 signal-to-signal or 
signal-to-COM voltage from exceeding 23 V if there is a 
transient overvoltage condition.

For Zone 2 applications, install a protection 

device between the external power supply and the 
NI 9871 V

sup

 and COM pins. The device must prevent the 

V

sup

-to-COM voltage from exceeding 39 V if there is a 

transient overvoltage condition.

This equipment has been evaluated as Ex nA IIC T4 equipment 
under DEMKO Certificate No. 07 ATEX 0626664X. Each module 
is marked 

 II 3G and is suitable for use in Zone 2 hazardous 

locations. If you are using the NI 9871 in Gas Group IIC hazardous 
locations or in ambient temperatures of –40 

°C ≤

 

Ta 

≤

 

70 

°C, you 

must use the device in an NI chassis or controller that has been 
evaluated as EEx nC IIC T4, Ex nA IIC T4, or Ex nL IIC T4 
equipment.