国家标准：爆炸性气体环境用电气设备通用要求。-National Standards: Electrical equipment for explosive gas atmospheres General requirements.

瓦斯测试仪CPLD部分程序，采用图表式编程，功能包括I/O扩展、分频、通信等。-The gas tester CPLD part of the program charts programming features include I/O expansion, divider, communications, and so on.