Wiki source code of MQTT Forward Instruction

Version 5.2 by Xiaoling on 2022/05/27 13:41

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1 **~ Contents:**
2
3 {{toc/}}
4
5
6 = 1. Introduction =
7
8 Dragino LoRa/LoRaWAN gateway support MQTT forwarding. It can forward the sensor data from LoRa network to MQTT server , and vice verse.
9
10
11 == 1.1 Support Devices ==
12
13 This MQTT forward instruction is for below devices:
14
15 * Firmware Version > LG02_LG08-5.3.1580178039 [[Firmware Download>>url:http://www.dragino.com/downloads/index.php?dir=LoRa_Gateway/LPS8/Firmware/Release/]]
16 * LG01N, OLG01N ((% style="color:red" %)**Warning**(%%): LG01-P LG01-S use another instruction: [[MQTT for LG01-P/LG01S>>url:https://wiki.dragino.com/index.php/Through_MQTT_to_upload_data]])
17 * LG02, OLG02
18 * LG308, DLOS8
19 * LPS8
20 * LIG16
21 * MS14 series if installed with the same firmware. (in this case, the MQTT forward will work , but no LoRa support)
22
23 = 2. Firmware Change Log for MQTT feature =
24
25 (((
26 This instruction is wrote start from LG02_LG08-5.3.1580178039. Below is related change log since this version of firmware.
27 )))
28
29 * LG02_LG08-5.3.1580178039
30 ** Initiate version
31
32 = 3. MQTT forward operating principle =
33
34 == 3.1 Network Structure ==
35
36 Below shows the network structure for MQTT forwarding.
37
38 * For Uplink: The sensor sends data to LoRa Gateway via LoRa wireless, The gateway will process these data and forward to remote MQTT Broker via Internet.
39 * For Downlink: The gateway subscribe a topic in the MQTT broker, when there is update on the topic, the gateway will know and broadcast the data to Local LoRa network,
40
41 [[image:image-20220527133547-1.png]]
42
43 General MQTT structure
44
45
46 == 3.2 How sensor data is forwarded ==
47
48 In this MQTT forward feature, the key point is how the gateway process the sensor data.
49
50
51 === 3.2.1 Upstream ===
52
53 Assume there are two sensor nodes, their ID are Node1 ID: 6734 , Node2 ID: 7456. In the remote MQTT broker there are two topics: Topic1: /channel/765800, Topic2: /channel/367860. We can set up in the gateway to map Node1 to Topic1 and Node2 to Topic2. So when there is a sensor data from Node1, the gateway will forward the data to Topic1, when there is sensor data from Node2, the gateway will forward to Topic2.
54
55 (((
56 The data flow works as below diagram.
57 )))
58
59 [[image:image-20220527134000-2.png]]
60
61 (((
62 Upstream path
63 )))
64
65 (((
66 Note: The sensor data can base or LoRa or other method, as long as there are data on the file /var/iot/channels. /span>
67 )))
68
69 (((
70
71 )))
72
73 === 3.2.2 Downstream ===
74
75 The gateway subscribes to a topic of the remote MQTT broker topic. When there is some one publish a value on this topic. The gateway will get it and broadcast to local LoRa Network.
76
77 (((
78 Below are the data flow for downstream.
79 )))
80
81 [[image:image-20220527134038-3.png]]
82
83 Downstream path
84
85
86 == 3.3 Macro Definition ==
87
88 The MQTT publish command use Macro settings to generate flexible upstream payload for MQTT publish.
89
90 (((
91 Currently the (% style="color:#4f81bd" %)**-t (topic)**(%%) and (% style="color:#4f81bd" %)**-m (message)**(%%) support Macros.
92 )))
93
94 === 3.3.1 -t topic macro ===
95
96 * CHANNEL: Remote Channel ID
97 * CLIENTID: Client ID , Same as -i
98 * WRITE_API: Remote Channel Write API
99 * USERNAME: User ID (-u)
100 * HOSTNAME: Device Hostname
101
102 === 3.3.2 -m message macro ===
103
104 * HOSTNAME: Device Hostname
105 * CHANNEL: Remote Channel ID
106 * DATA: Sensor Data without time stamp and rssi
107 * META: Completely sensor data with time stamp and rssi
108 * JSON: Convert META to json format.
109
110 === 3.3.3 Example for Macro ===
111
112 [[image:https://wiki.dragino.com/images/thumb/c/c7/MQTT_Command_9.png/600px-MQTT_Command_9.png||height="385" width="600"]]
113
114 MQTT Publish configure
115
116 Above screen shots shows below format:
117
118 * -t: CLIENTID/CHANNEL/data
119 * -m: DATA
120
121 When there is a LoRa sensor arrive. it will be store at the /var/iot/channels as below:
122
123 [[image:https://wiki.dragino.com/images/thumb/c/c4/MQTT_Command_20.png/600px-MQTT_Command_20.png||height="325" width="600"]]
124
125 Sensor Data
126
127 (((
128 According to above macro. Gateway will publish (% class="mark" %)**field1=22.0&field2=49.0**(%%) to topic: (% class="mark" %)**dragino-1b7060/78901/data**(%%), where 78901 is the remote channel for this node ID.
129 )))
130
131
132 == 3.4 Modify the MQTT to support more options ==
133
134 The MQTT Client Utility used in Dragino is **mosquitto_pub** and **mosquitto_sub**. User can add more options to the mqtt commands. User can check the valid options by command mosquitto_pub ~-~-help. as below:
135
136 (% class="box" %)
137 (((
138 root@dragino-1ec39c:~~# mosquitto_pub ~-~-help
139 mosquitto_pub is a simple mqtt client that will publish a message on a single topic and exit.
140 mosquitto_pub version 1.6.4 running on libmosquitto 1.6.4.
141 \\Usage: mosquitto_pub {[-h host] [-p port] [-u username] [-P password] -t topic | -L URL}
142 {-f file | -l | -n | -m message}
143 [-c] [-k keepalive] [-q qos] [-r] [~-~-repeat N] [~-~-repeat-delay time]
144 [-A bind_address]
145 [-i id] [-I id_prefix]
146 [-d] [~-~-quiet]
147 [-M max_inflight]
148 [-u username [-P password]]
149 [~-~-will-topic [~-~-will-payload payload] [~-~-will-qos qos] [~-~-will-retain]]
150 [{~-~-cafile file | ~-~-capath dir} [~-~-cert file] [~-~-key file]
151 [~-~-ciphers ciphers] [~-~-insecure]
152 [~-~-tls-alpn protocol]
153 [~-~-tls-engine engine] [~-~-keyform keyform] [~-~-tls-engine-kpass-sha1]]
154 [~-~-psk hex-key ~-~-psk-identity identity [~-~-ciphers ciphers]]
155 [~-~-proxy socks-url]
156 [~-~-property command identifier value]
157 [-D command identifier value]
158 mosquitto_pub ~-~-help
159 \\-A : bind the outgoing socket to this host/ip address. Use to control which interface
160 the client communicates over.
161 -d : enable debug messages.
162 -D : Define MQTT v5 properties. See the documentation for more details.
163 -f : send the contents of a file as the message.
164 -h : mqtt host to connect to. Defaults to localhost.
165 -i : id to use for this client. Defaults to mosquitto_pub_ appended with the process id.
166 -I : define the client id as id_prefix appended with the process id. Useful for when the
167 broker is using the clientid_prefixes option.
168 -k : keep alive in seconds for this client. Defaults to 60.
169 -L : specify user, password, hostname, port and topic as a URL in the form:
170 mqtt(s):~/~/[username[:password]@]host[:port]/topic
171 -l : read messages from stdin, sending a separate message for each line.
172 -m : message payload to send.
173 -M : the maximum inflight messages for QoS 1/2..
174 -n : send a null (zero length) message.
175 -p : network port to connect to. Defaults to 1883 for plain MQTT and 8883 for MQTT over TLS.
176 -P : provide a password
177 -q : quality of service level to use for all messages. Defaults to 0.
178 -r : message should be retained.
179 -s : read message from stdin, sending the entire input as a message.
180 -t : mqtt topic to publish to.
181 -u : provide a username
182 -V : specify the version of the MQTT protocol to use when connecting.
183 Can be mqttv5, mqttv311 or mqttv31. Defaults to mqttv311.
184 ~-~-help : display this message.
185 ~-~-repeat : if publish mode is -f, -m, or -s, then repeat the publish N times.
186 ~-~-repeat-delay : if using ~-~-repeat, wait time seconds between publishes. Defaults to 0.
187 ~-~-quiet : (% class="mark" %)don't print error messages.
188 ~-~-will-payload : payload for the client Will, which is sent by the broker in case of
189 unexpected disconnection. If not given and will-topic is set, a zero
190 length message will be sent.
191 ~-~-will-qos : QoS level for the client Will.
192 ~-~-will-retain : if given, make the client Will retained.
193 ~-~-will-topic : the topic on which to publish the client Will.
194 ~-~-cafile : path to a file containing trusted CA certificates to enable encrypted
195 communication.
196 ~-~-capath : path to a directory containing trusted CA certificates to enable encrypted
197 communication.
198 ~-~-cert : client certificate for authentication, if required by server.
199 ~-~-key : client private key for authentication, if required by server.
200 ~-~-keyform : keyfile type, can be either "pem" or "engine".
201 ~-~-ciphers : openssl compatible list of TLS ciphers to support.
202 ~-~-tls-version : TLS protocol version, can be one of tlsv1.3 tlsv1.2 or tlsv1.1.
203 Defaults to tlsv1.2 if available.
204 ~-~-insecure : do not check that the server certificate hostname matches the remote
205 hostname. Using this option means that you cannot be sure that the
206 remote host is the server you wish to connect to and so is insecure.
207 Do not use this option in a production environment.
208 ~-~-tls-engine : If set, enables the use of a TLS engine device.
209 ~-~-tls-engine-kpass-sha1 : SHA1 of the key password to be used with the selected SSL engine.
210 ~-~-psk : pre-shared-key in hexadecimal (no leading 0x) to enable TLS-PSK mode.
211 ~-~-psk-identity : client identity string for TLS-PSK mode.
212 ~-~-proxy : SOCKS5 proxy URL of the form:
213 socks5h:~/~/[username[:password]@]hostname[:port]
214 Only "none" and "username" authentication is supported.
215 \\See https:~/~/mosquitto.org/ for more information.
216 )))
217
218
219 (((
220 and modify the /usr/bin/mqtt_process.sh script, the location to change the command option is below lines:
221 )))
222
223 (% class="box" %)
224 (((
225 # Call MQTT Publish command
226 \\# 1. Case with User, Password and Client ID present  (e.g. Azure)
227 if [ ! -z "$pass" ] && [ ! -z "$user" ] && [ ! -z "$clientID" ]; then
228 case="1" 
229 mosquitto_pub $D -h $server -p $port -q $pub_qos -i $clientID -t $pub_topic -u $user -P "$pass" $C $cafile $PUB_FLAG "$mqtt_data"
230 \\# 2. Case with Certificate, Key and ClientID present (e.g. AWS)
231 elif [ ! -z "$certfile" ] && [ ! -z "$key" ] && [ ! -z "$clientID" ]; then
232 case="2" 
233 mosquitto_pub $D -h $server -p $port -q $pub_qos -i $clientID -t $pub_topic ~-~-cert $cert ~-~-key $key $C $cafile $PUB_FLAG "$mqtt_data"
234 \\# 3. Case with no User, Certificate or ClientID present
235 elif [ -z "$user" ] && [ -z "$certfile" ] && [ -z "$clientID" ]; then
236 case="3" 
237 mosquitto_pub $D -h $server -p $port -q $pub_qos -t $pub_topic $PUB_FLAG "$mqtt_data"
238 \\# 4. Case with no User, Certificate, but with ClientID present
239 elif [ -z "$user" ] && [ -z "$certfile" ] && [ ! -z "$clientID" ]; then
240 case="4" 
241 mosquitto_pub $D -h $server -p $port -q $pub_qos -i $clientID -t $pub_topic $PUB_FLAG "$mqtt_data"
242 \\# 5. Case with User and ClientID present, but no Password and no Certificate present
243 elif [ -z "$pass" ] && [ -z "$certfile" ] && [ ! -z "$user" ] && [ ! -z "$clientID" ]; then
244 case="5" 
245 mosquitto_pub $D -h $server -p $port -q $pub_qos -i $clientID -t $pub_topic -u $user $PUB_FLAG "$mqtt_data"
246 \\# 6. Case with User and Password present, but no ClientID and no Certificate present
247 elif [ ! -z "$user" ] && [ ! -z "$pass" ] && [ -z "$clientID" ] && [ -z "$certfile" ]; then
248 case="6" 
249 mosquitto_pub $D -h $server -p $port -q $pub_qos  -t $pub_topic -u $user -P "$pass" $PUB_FLAG "$mqtt_data"
250 \\# 0. Else - invalid parameters, just log
251 else
252 case="Invalid parameters" 
253 logger "[IoT.MQTT]:Invalid Parameters - mosquitto_pub not called."
254 fi
255 )))
256
257
258 = 4. Example to communicate to a simple MQTT server =
259
260 == 4.1 Overview ==
261
262 This section is an example to show how to set up LG01-N to communicate with a MQTT server. The MQTT server is a simple utility set up in a local PC. Note: User can set up same server via [[this instruction>>url:http://www.steves-internet-guide.com/install-mosquitto-broker/]].
263
264 == 4.2 Simulate via MQTT.fx utility ==
265
266 The [[MQTT.fx>>url:http://mqttfx.jensd.de/index.php/download]] is a MQTT client tool. We can use this to simulate a MQTT connection to our MQTT broker first to make sure the MQTT broker works. This will also help us understand how it works.
267
268 (((
269 In this test, the MQTT broker and MQTT.fx are installed in the same PC, so the MQTT server address in MQTT.fx should be localhost. Below shows how to connect to the server.
270 )))
271
272 [[image:https://wiki.dragino.com/images/thumb/0/06/MQTT_Forward_4.png/600px-MQTT_Forward_4.png||height="201" width="600"]]
273
274 Connect to MQTT Broker
275
276 After connected, use publish to public some thing to MQTT server. This to simulate upsteam
277
278 [[image:https://wiki.dragino.com/images/thumb/b/bd/MQTT_Forward_5.png/600px-MQTT_Forward_5.png||height="149" width="600"]]
279
280 Upstream: Publish message to MQTT Broker
281
282 To simulate a downstream, use MQTT.fx to subscribe a topic, and publish something to this topic. as Below:
283
284 [[image:https://wiki.dragino.com/images/thumb/3/3d/MQTT_Forward_6.png/600px-MQTT_Forward_6.png||height="279" width="600"]]
285
286 Downstream: Subscribe a topic to get downstream
287
288
289 == 4.3 Simulate via Dragino Command Line ==
290
291 For first try of MQTT connection, simulate via command line is recommend, there are many servers / connection type for MQTT. They are using different connection parameters. Simulating the connection via command line will help us rapidly connect to server and debug.
292
293 In the Dragino Gateway, we use [[mosquitto client>>url:https://mosquitto.org/]] for MQTT connection.
294
295
296 (% class="mark" %)**For Upstream**
297
298 command is [[mosquitto_pub>>url:https://mosquitto.org/man/mosquitto_pub-1.html]]
299
300 Example: mosquitto_pub -h 192.168.199.148 -p 1883 -t /channel/6543 -m temp=36
301
302 Note: 192.168.199.148 is MQTT broker address, the gateway and the MQTT broker PC are in the same network.
303
304 [[image:https://wiki.dragino.com/images/thumb/d/d0/MQTT_Command_6.png/600px-MQTT_Command_6.png||height="188" width="600"]]
305
306 mosquitto_pub
307
308
309 (% class="mark" %)**For Downstream**
310
311 Use [[mosquitto_sub>>url:https://mosquitto.org/man/mosquitto_sub-1.html]] to subscribe the change on the topic.
312
313 [[image:https://wiki.dragino.com/images/thumb/8/89/MQTT_Command_7.png/600px-MQTT_Command_7.png||height="267" width="600"]]
314
315 mosquitto_sub
316
317
318 == 4.4 Configure Dragino UI for MQTT connection ==
319
320 This chapter are step by step to show to configure the Dragino Menu for MQTT auto connection.
321
322 (((
323 Go to (% class="mark" %)**Dragino Menu ~-~-> MQTT Client**
324 )))
325
326 [[image:https://wiki.dragino.com/images/thumb/b/bc/MQTT_Command_8.png/600px-MQTT_Command_8.png||height="249" width="600"]]
327
328 go to mqtt configure menu
329
330 (((
331 Select **Forward to MQTT server**. (% class="mark" %)**Notice**(%%): This option is removed from the latest firmware, in the latest firmware, if user submit "SAVE & APPLY" in MQTT page, the gateway will use MQTT service.
332 )))
333
334 [[image:https://wiki.dragino.com/images/thumb/1/14/MQTT_Commands_8.png/600px-MQTT_Commands_8.png||height="240" width="600"]]
335
336 forward to MQTT
337
338
339 === 4.4.1 Configure the MQTT Client for Upstream ===
340
341 Below screenshot is same as the publish command:
342
343 (% class="box" %)
344 (((
345 mosquitto_pub -h 192.168.199.148 -p 1883 -i dragino-1b7060 -t CLIENTID/CHANNEL/data -m DATA
346 ~/~/where the CLIENTID, CHANNEL & DATA are macro. represent for
347 ~/~/CLIENTID: dragino-1b7060
348 ~/~/CHANNEL: Remote ID in Channel settings; here is 78901 or 567456
349 ~/~/DATA: The data stores in /var/iot/channels/
350 )))
351
352 [[image:https://wiki.dragino.com/images/thumb/c/c7/MQTT_Command_9.png/600px-MQTT_Command_9.png||height="385" width="600"]]
353
354 MQTT Publish configure
355
356
357 [[image:https://wiki.dragino.com/images/thumb/b/b7/MQTT_Command_10.png/600px-MQTT_Command_10.png||height="544" width="600"]]
358
359 MQTT Channel settings
360
361 (((
362 For example, if we put a data(temp=46) on the file /var/iot/channels/4567, because 4567 match the remote channel 78901. the gateway will run this command:
363 )))
364
365 (% class="box" %)
366 (((
367 mosquitto_pub -h 192.168.199.148 -p 1883 -i dragino-1b7060 -t dragino-1b7060/78901/data -m temp=46
368 )))
369
370 (((
371 to MQTT broker.
372 )))
373
374
375 (((
376 Below is a simulation to put this data to active the MQTT publish.
377 )))
378
379 [[image:https://wiki.dragino.com/images/thumb/3/30/MQTT_Command_11.png/600px-MQTT_Command_11.png||height="308" width="600"]]
380
381 MQTT Publish
382
383
384 === 4.4.2 Configure the MQTT Client for Downstream ===
385
386 Below screen shot equal to this subscribe command:
387
388 (% class="box" %)
389 (((
390 mosquitto_sub -h 192.168.199.148 -p 1883 -i dragino-1b7060 -t command.
391 )))
392
393 [[image:https://wiki.dragino.com/images/3/36/MQTT_Command_12.png||height="173" width="579"]]
394
395 MQTT Subscribe
396
397
398 (((
399 When MQTT broker receive a update on this topic, the gateway will get the update and use LoRa radio to broadcast this message. The LoRa parameters used for update is:
400 )))
401
402 [[image:https://wiki.dragino.com/images/thumb/b/b8/MQTT_Command_13.png/600px-MQTT_Command_13.png||height="300" width="600"]]
403
404 LoRa Broadcast parameters.
405
406
407 And below is the subscribe simulation:
408
409 [[image:https://wiki.dragino.com/images/thumb/6/60/MQTT_Command_14.png/600px-MQTT_Command_14.png||height="255" width="600"]]
410
411 downstream simulation
412
413
414 == 4.5 Add LoRa support to communicate with remote sensor ==
415
416 In above section, we have configured the UI to support MQTT upstream and downstream. We can simulate via Linux command. In this section, we will guide how to communicate with remote LoRa End Node for upstream and downstream.
417
418 === 4.5.1 Use LoRa Raw protocol for communication ~-~- For LG01/LG02 ===
419
420 (((
421 We can use [[LoRa Shield>>url:http://www.dragino.com/products/lora/item/102-lora-shield.html]] to send LoRa Raw data to Gateway and receive data from gateway.
422 )))
423
424 (((
425 The example Sketch for LoRa Shield +Arduino is here: [[LoRa_Shield_Sketch_For_MQTT>>url:http://www.dragino.com/downloads/index.php?dir=LoraShield/]]
426 )))
427
428 (((
429 And this link is the required library: [[arduino-LoRa-master>>url:http://www.dragino.com/downloads/index.php?dir=LoraShield/]]. Unzip this library and put in Arduino library location.
430 )))
431
432 (((
433 What does the Arduino Sketch do? The Arduino Sketch will:
434 )))
435
436 * Upstream: Keep sending a LoRa Message every minutes with this payload : <4567>tem=xx&hum=yy (Where xx and yy are temperature and humidity value generated randomly).
437 * Downstream: Listening broadcast message from gateway, and print it in console.
438 * The LoRa parameter settings in Arduino should match the LoRa settings in gateway, as below:
439
440 [[image:https://wiki.dragino.com/images/thumb/3/3b/MQTT_Command_17.png/600px-MQTT_Command_17.png||height="197" width="600"]]
441
442 LoRa Parameter should match
443
444
445 Below is the test result after the Arduino Sketch is running.
446
447 [[image:https://wiki.dragino.com/images/thumb/6/63/MQTT_Command_18.png/600px-MQTT_Command_18.png||height="319" width="600"]]
448
449 Upstream Data Flow
450
451 [[image:https://wiki.dragino.com/images/thumb/1/18/MQTT_Command_19.png/600px-MQTT_Command_19.png||height="309" width="600"]]
452
453 Downstream Data Flow
454
455
456 === 4.5.2 Use LoRaWAN Protocol for communication ~-~- For LG308/LPS8/DLOS8 ===
457
458 (((
459 Since firmware (% class="mark" %)**LG02_LG08~-~-build-v5.3.1585192026-20200326-1109,**(%%) Dragino LoRaWAN gateways support the communication to LoRaWAN (% class="mark" %)**ABP end node**(%%) locally without the need of LoRaWAN server. This feature allow us to integrate MQTT in the gateway to support LoRaWAN to MQTT forwarding or visa verse.
460 )))
461
462 (((
463 When use test this feature, please use the version higher then : (% class="mark" %)**LG02_LG08~-~-build-v5.4.1593400722-20200629-1120**(%%), in this version, the upload format is changed and readable, which is easier for integration.
464 (% class="mark" %)**Video Instruction**(%%):[[https:~~/~~/youtu.be/qJTY441-t90>>url:https://youtu.be/qJTY441-t90]]
465 )))
466
467 (((
468 **Step 1**: Refer [[Communicate with ABP End Node>>url:https://wiki.dragino.com/index.php/Communication_with_ABP_End_Node]] to know how to set up LG308 to work with LoRaWAN End node.
469 )))
470
471 (((
472 **Step 2**: Make sure your Radio settings match the End Node settings.
473 )))
474
475 [[image:https://wiki.dragino.com/images/thumb/f/f7/LG308_MQTT_5.png/600px-LG308_MQTT_5.png||height="387" width="600"]]
476
477 Use Same Frequency Band as End Node
478
479
480 (((
481 (((
482 **Step 3**: Set up publish format and MQTT channel. The LG308 will store the Data from End node in HEX format in the file. And we need to config the format to META
483 )))
484 )))
485
486 [[image:https://wiki.dragino.com/images/thumb/8/8d/LG308_MQTT_3.png/600px-LG308_MQTT_3.png||height="385" width="600"]]
487
488 Publish mush use META as data format for LG308
489
490
491 **Step 4**: Map the Device Address to Remote ID in MQTT server.
492
493 [[image:https://wiki.dragino.com/images/thumb/7/7f/LG308_MQTT_4.png/600px-LG308_MQTT_4.png||height="335" width="600"]]
494
495 Map Dev Addr to remote ID
496
497
498 **Step 5: Upstream**: Save the change, we can see the log info via "sytem log", End Node and MQTT Server
499
500 [[image:https://wiki.dragino.com/images/thumb/b/be/LG308_MQTT_6.png/600px-LG308_MQTT_6.png||height="279" width="600"]]
501
502 Upstream Process
503
504 [[image:https://wiki.dragino.com/images/thumb/0/07/LG308_MQTT_6_1.png/600px-LG308_MQTT_6_1.png||height="246" width="600"]]
505
506 Choose ASCII Format
507
508 [[image:https://wiki.dragino.com/images/thumb/a/a3/LG308_MQTT_6_2.png/600px-LG308_MQTT_6_2.png||height="248" width="600"]]
509
510 LHT65 Decoder
511
512
513 **Step 6: Set up subscribe:** Subscribe a topci for downstream.
514
515 [[image:https://wiki.dragino.com/images/thumb/b/b9/LG308_MQTT_7.png/600px-LG308_MQTT_7.png||height="176" width="600"]]
516
517 Subscribe to a topic
518
519
520 **Step 7**: Downstream: Save the change, we can see the log info via "sytem log", End Node and MQTT Server.
521
522 [[image:https://wiki.dragino.com/images/thumb/9/97/LG308_MQTT_8.png/600px-LG308_MQTT_8.png||height="298" width="600"]]
523
524 Downstream Flow
525
526 (% class="mark" %)**Notice: The text use for Downstream must meet the requirement from [[LG308 Downstream Payload>>url:https://wiki.dragino.com/index.php/Communication_with_ABP_End_Node#Downstream]]**
527
528
529 = 5. Example For Different MQTT Servers =
530
531 (% style="width:731.222px" %)
532 |=(% style="width: 270px;" %)(((
533 [[image:https://wiki.dragino.com/images/thumb/7/73/ThingSpeak1.png/200px-ThingSpeak1.png||alt="ThingSpeak1.png" height="114" width="233"]]
534
535 == [[ThingSpeak Server>>url:http://www.thingspeak.com/]] ==
536
537
538 [[Examples>>url:https://wiki.dragino.com/index.php/ThingSpeak_Examples]]
539 )))|=(% style="width: 242px;" %)(((
540 [[image:https://wiki.dragino.com/images/thumb/3/3b/Lewei50.png/200px-Lewei50.png||alt="Lewei50.png" height="65" width="223"]]
541
542
543 == [[乐联网平台>>url:https://www.lewei50.com/]] ==
544
545
546 [[lewei Example>>url:https://wiki.dragino.com/index.php/Lewei_Example_mqtt]]
547 )))|=(% style="width: 214px;" %)(((
548 [[image:https://wiki.dragino.com/images/thumb/a/aa/AWS-IOT.png/200px-AWS-IOT.png||alt="AWS-IOT.png" height="112" width="183"]]
549
550 == [[AWS-IOT>>url:https://aws.amazon.com/cn/iot-platform/how-it-works/]] ==
551
552
553 [[AWS Examples>>url:https://wiki.dragino.com/index.php/MQTT_Forward_to_Amazon_AWS-IOT]]
554 )))
555
556 = 6. How to Debug =
557
558 User can login the gateway's console and run (% class="mark" %)**logread -f**(%%). It will shows the output when there is packet arrive.User can see if it is correct.
559
560 = 7. How to ask for Support =
561
562 If a user still not have trouble making it works. please send a mail to support@dragino.com with the below info:
563
564 * Detail of your LoRaWAN end node.
565 * Gateway Model and firmware version
566 * A set of screenshots you configure in the gateway according to our instruction
567 * A full log of "logread -f"