网关做MB从机外部主机通过485控制网关上面的DIDOAI

适用于新款设备，不使用虚拟设备的，使用虚拟设备的更简单，启用一下就行了。

参考配置
{"type":"base","version":"V4","base":{"host":"","param_ver":8,"flow":0,"fota":1,"log":1,"ntp":0,"nnt":-1,"shell":[1,120,1],"report":1,"pmod":0,"pswd":"","pins":[13,8,12],"reboot":0,"mqr":[1,20,100,1],"lbs":1,"ofm":0,"eth":[1,"","","",0],"dns1":["114.114.114.114","114.114.114.114"],"apn":[0,"","",""]},"uconf":[[1,9600,8,0,1,19,1,20,"",50],[],[3,115200,8,0,1,18,1,20,"",0]],"nconf":[[],[],[],[],[],[]],"pnconf":[[]],"param_ver":8,"h2r":[],"mb":[[2,1,21,[3],1,0,0,"","","",0,100,0,5,3,0,1],[[10,96,"010300820004","3"],[["AI1",130,"f",1],["AI2",132,"f",1]]],[[10,96,"01030096000c","3"],[["DI1",150,"H",1],["DI2",151,"H",1],["DO1",160,"H",1],["DO2",161,"H",1]]]],"d6":[],"szy":[],"l6":[],"up":{},"vd":{},"rule":[[36,35,4,"",[],[[5,"","function()\nsys.subscribe(\"D_RECV_1\", \"D_SEND_3\")\nsys.subscribe(\"D_RECV_3\", \"D_SEND_1\")\nend"]]]],"lp":[],"tts":[]}

原理:
新款硬件，外设是接在串口3上面的一个modbus从机， 网关modbus通过串口3读取。但是外部主机要从串口1访问，就需要把串口1和串口3桥接， 以上配置，通过场景联动实现串口1和串口3桥接， 外部发给4851的数据会转发给串口3，返回同理