Wiki source code of MQTT Forward Instruction

Version 6.2 by Xiaoling on 2022/05/27 13:42

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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 )))
95
96 === 3.3.1 -t topic macro ===
97
98 * CHANNEL: Remote Channel ID
99 * CLIENTID: Client ID , Same as -i
100 * WRITE_API: Remote Channel Write API
101 * USERNAME: User ID (-u)
102 * HOSTNAME: Device Hostname
103
104
105 === 3.3.2 -m message macro ===
106
107 * HOSTNAME: Device Hostname
108 * CHANNEL: Remote Channel ID
109 * DATA: Sensor Data without time stamp and rssi
110 * META: Completely sensor data with time stamp and rssi
111 * JSON: Convert META to json format.
112
113
114 === 3.3.3 Example for Macro ===
115
116 [[image:image-20220527134251-4.png]]
117
118 MQTT Publish configure
119
120 Above screen shots shows below format:
121
122 * -t: CLIENTID/CHANNEL/data
123 * -m: DATA
124
125 When there is a LoRa sensor arrive. it will be store at the /var/iot/channels as below:
126
127 [[image:https://wiki.dragino.com/images/thumb/c/c4/MQTT_Command_20.png/600px-MQTT_Command_20.png||height="325" width="600"]]
128
129 Sensor Data
130
131 (((
132 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.
133 )))
134
135
136 == 3.4 Modify the MQTT to support more options ==
137
138 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:
139
140 (% class="box" %)
141 (((
142 root@dragino-1ec39c:~~# mosquitto_pub ~-~-help
143 mosquitto_pub is a simple mqtt client that will publish a message on a single topic and exit.
144 mosquitto_pub version 1.6.4 running on libmosquitto 1.6.4.
145 \\Usage: mosquitto_pub {[-h host] [-p port] [-u username] [-P password] -t topic | -L URL}
146 {-f file | -l | -n | -m message}
147 [-c] [-k keepalive] [-q qos] [-r] [~-~-repeat N] [~-~-repeat-delay time]
148 [-A bind_address]
149 [-i id] [-I id_prefix]
150 [-d] [~-~-quiet]
151 [-M max_inflight]
152 [-u username [-P password]]
153 [~-~-will-topic [~-~-will-payload payload] [~-~-will-qos qos] [~-~-will-retain]]
154 [{~-~-cafile file | ~-~-capath dir} [~-~-cert file] [~-~-key file]
155 [~-~-ciphers ciphers] [~-~-insecure]
156 [~-~-tls-alpn protocol]
157 [~-~-tls-engine engine] [~-~-keyform keyform] [~-~-tls-engine-kpass-sha1]]
158 [~-~-psk hex-key ~-~-psk-identity identity [~-~-ciphers ciphers]]
159 [~-~-proxy socks-url]
160 [~-~-property command identifier value]
161 [-D command identifier value]
162 mosquitto_pub ~-~-help
163 \\-A : bind the outgoing socket to this host/ip address. Use to control which interface
164 the client communicates over.
165 -d : enable debug messages.
166 -D : Define MQTT v5 properties. See the documentation for more details.
167 -f : send the contents of a file as the message.
168 -h : mqtt host to connect to. Defaults to localhost.
169 -i : id to use for this client. Defaults to mosquitto_pub_ appended with the process id.
170 -I : define the client id as id_prefix appended with the process id. Useful for when the
171 broker is using the clientid_prefixes option.
172 -k : keep alive in seconds for this client. Defaults to 60.
173 -L : specify user, password, hostname, port and topic as a URL in the form:
174 mqtt(s):~/~/[username[:password]@]host[:port]/topic
175 -l : read messages from stdin, sending a separate message for each line.
176 -m : message payload to send.
177 -M : the maximum inflight messages for QoS 1/2..
178 -n : send a null (zero length) message.
179 -p : network port to connect to. Defaults to 1883 for plain MQTT and 8883 for MQTT over TLS.
180 -P : provide a password
181 -q : quality of service level to use for all messages. Defaults to 0.
182 -r : message should be retained.
183 -s : read message from stdin, sending the entire input as a message.
184 -t : mqtt topic to publish to.
185 -u : provide a username
186 -V : specify the version of the MQTT protocol to use when connecting.
187 Can be mqttv5, mqttv311 or mqttv31. Defaults to mqttv311.
188 ~-~-help : display this message.
189 ~-~-repeat : if publish mode is -f, -m, or -s, then repeat the publish N times.
190 ~-~-repeat-delay : if using ~-~-repeat, wait time seconds between publishes. Defaults to 0.
191 ~-~-quiet : (% class="mark" %)don't print error messages.
192 ~-~-will-payload : payload for the client Will, which is sent by the broker in case of
193 unexpected disconnection. If not given and will-topic is set, a zero
194 length message will be sent.
195 ~-~-will-qos : QoS level for the client Will.
196 ~-~-will-retain : if given, make the client Will retained.
197 ~-~-will-topic : the topic on which to publish the client Will.
198 ~-~-cafile : path to a file containing trusted CA certificates to enable encrypted
199 communication.
200 ~-~-capath : path to a directory containing trusted CA certificates to enable encrypted
201 communication.
202 ~-~-cert : client certificate for authentication, if required by server.
203 ~-~-key : client private key for authentication, if required by server.
204 ~-~-keyform : keyfile type, can be either "pem" or "engine".
205 ~-~-ciphers : openssl compatible list of TLS ciphers to support.
206 ~-~-tls-version : TLS protocol version, can be one of tlsv1.3 tlsv1.2 or tlsv1.1.
207 Defaults to tlsv1.2 if available.
208 ~-~-insecure : do not check that the server certificate hostname matches the remote
209 hostname. Using this option means that you cannot be sure that the
210 remote host is the server you wish to connect to and so is insecure.
211 Do not use this option in a production environment.
212 ~-~-tls-engine : If set, enables the use of a TLS engine device.
213 ~-~-tls-engine-kpass-sha1 : SHA1 of the key password to be used with the selected SSL engine.
214 ~-~-psk : pre-shared-key in hexadecimal (no leading 0x) to enable TLS-PSK mode.
215 ~-~-psk-identity : client identity string for TLS-PSK mode.
216 ~-~-proxy : SOCKS5 proxy URL of the form:
217 socks5h:~/~/[username[:password]@]hostname[:port]
218 Only "none" and "username" authentication is supported.
219 \\See https:~/~/mosquitto.org/ for more information.
220 )))
221
222
223 (((
224 and modify the /usr/bin/mqtt_process.sh script, the location to change the command option is below lines:
225 )))
226
227 (% class="box" %)
228 (((
229 # Call MQTT Publish command
230 \\# 1. Case with User, Password and Client ID present  (e.g. Azure)
231 if [ ! -z "$pass" ] && [ ! -z "$user" ] && [ ! -z "$clientID" ]; then
232 case="1" 
233 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"
234 \\# 2. Case with Certificate, Key and ClientID present (e.g. AWS)
235 elif [ ! -z "$certfile" ] && [ ! -z "$key" ] && [ ! -z "$clientID" ]; then
236 case="2" 
237 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"
238 \\# 3. Case with no User, Certificate or ClientID present
239 elif [ -z "$user" ] && [ -z "$certfile" ] && [ -z "$clientID" ]; then
240 case="3" 
241 mosquitto_pub $D -h $server -p $port -q $pub_qos -t $pub_topic $PUB_FLAG "$mqtt_data"
242 \\# 4. Case with no User, Certificate, but with ClientID present
243 elif [ -z "$user" ] && [ -z "$certfile" ] && [ ! -z "$clientID" ]; then
244 case="4" 
245 mosquitto_pub $D -h $server -p $port -q $pub_qos -i $clientID -t $pub_topic $PUB_FLAG "$mqtt_data"
246 \\# 5. Case with User and ClientID present, but no Password and no Certificate present
247 elif [ -z "$pass" ] && [ -z "$certfile" ] && [ ! -z "$user" ] && [ ! -z "$clientID" ]; then
248 case="5" 
249 mosquitto_pub $D -h $server -p $port -q $pub_qos -i $clientID -t $pub_topic -u $user $PUB_FLAG "$mqtt_data"
250 \\# 6. Case with User and Password present, but no ClientID and no Certificate present
251 elif [ ! -z "$user" ] && [ ! -z "$pass" ] && [ -z "$clientID" ] && [ -z "$certfile" ]; then
252 case="6" 
253 mosquitto_pub $D -h $server -p $port -q $pub_qos  -t $pub_topic -u $user -P "$pass" $PUB_FLAG "$mqtt_data"
254 \\# 0. Else - invalid parameters, just log
255 else
256 case="Invalid parameters" 
257 logger "[IoT.MQTT]:Invalid Parameters - mosquitto_pub not called."
258 fi
259 )))
260
261
262 = 4. Example to communicate to a simple MQTT server =
263
264 == 4.1 Overview ==
265
266 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/]].
267
268 == 4.2 Simulate via MQTT.fx utility ==
269
270 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.
271
272 (((
273 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.
274 )))
275
276 [[image:https://wiki.dragino.com/images/thumb/0/06/MQTT_Forward_4.png/600px-MQTT_Forward_4.png||height="201" width="600"]]
277
278 Connect to MQTT Broker
279
280 After connected, use publish to public some thing to MQTT server. This to simulate upsteam
281
282 [[image:https://wiki.dragino.com/images/thumb/b/bd/MQTT_Forward_5.png/600px-MQTT_Forward_5.png||height="149" width="600"]]
283
284 Upstream: Publish message to MQTT Broker
285
286 To simulate a downstream, use MQTT.fx to subscribe a topic, and publish something to this topic. as Below:
287
288 [[image:https://wiki.dragino.com/images/thumb/3/3d/MQTT_Forward_6.png/600px-MQTT_Forward_6.png||height="279" width="600"]]
289
290 Downstream: Subscribe a topic to get downstream
291
292
293 == 4.3 Simulate via Dragino Command Line ==
294
295 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.
296
297 In the Dragino Gateway, we use [[mosquitto client>>url:https://mosquitto.org/]] for MQTT connection.
298
299
300 (% class="mark" %)**For Upstream**
301
302 command is [[mosquitto_pub>>url:https://mosquitto.org/man/mosquitto_pub-1.html]]
303
304 Example: mosquitto_pub -h 192.168.199.148 -p 1883 -t /channel/6543 -m temp=36
305
306 Note: 192.168.199.148 is MQTT broker address, the gateway and the MQTT broker PC are in the same network.
307
308 [[image:https://wiki.dragino.com/images/thumb/d/d0/MQTT_Command_6.png/600px-MQTT_Command_6.png||height="188" width="600"]]
309
310 mosquitto_pub
311
312
313 (% class="mark" %)**For Downstream**
314
315 Use [[mosquitto_sub>>url:https://mosquitto.org/man/mosquitto_sub-1.html]] to subscribe the change on the topic.
316
317 [[image:https://wiki.dragino.com/images/thumb/8/89/MQTT_Command_7.png/600px-MQTT_Command_7.png||height="267" width="600"]]
318
319 mosquitto_sub
320
321
322 == 4.4 Configure Dragino UI for MQTT connection ==
323
324 This chapter are step by step to show to configure the Dragino Menu for MQTT auto connection.
325
326 (((
327 Go to (% class="mark" %)**Dragino Menu ~-~-> MQTT Client**
328 )))
329
330 [[image:https://wiki.dragino.com/images/thumb/b/bc/MQTT_Command_8.png/600px-MQTT_Command_8.png||height="249" width="600"]]
331
332 go to mqtt configure menu
333
334 (((
335 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.
336 )))
337
338 [[image:https://wiki.dragino.com/images/thumb/1/14/MQTT_Commands_8.png/600px-MQTT_Commands_8.png||height="240" width="600"]]
339
340 forward to MQTT
341
342
343 === 4.4.1 Configure the MQTT Client for Upstream ===
344
345 Below screenshot is same as the publish command:
346
347 (% class="box" %)
348 (((
349 mosquitto_pub -h 192.168.199.148 -p 1883 -i dragino-1b7060 -t CLIENTID/CHANNEL/data -m DATA
350 ~/~/where the CLIENTID, CHANNEL & DATA are macro. represent for
351 ~/~/CLIENTID: dragino-1b7060
352 ~/~/CHANNEL: Remote ID in Channel settings; here is 78901 or 567456
353 ~/~/DATA: The data stores in /var/iot/channels/
354 )))
355
356 [[image:https://wiki.dragino.com/images/thumb/c/c7/MQTT_Command_9.png/600px-MQTT_Command_9.png||height="385" width="600"]]
357
358 MQTT Publish configure
359
360
361 [[image:https://wiki.dragino.com/images/thumb/b/b7/MQTT_Command_10.png/600px-MQTT_Command_10.png||height="544" width="600"]]
362
363 MQTT Channel settings
364
365 (((
366 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:
367 )))
368
369 (% class="box" %)
370 (((
371 mosquitto_pub -h 192.168.199.148 -p 1883 -i dragino-1b7060 -t dragino-1b7060/78901/data -m temp=46
372 )))
373
374 (((
375 to MQTT broker.
376 )))
377
378
379 (((
380 Below is a simulation to put this data to active the MQTT publish.
381 )))
382
383 [[image:https://wiki.dragino.com/images/thumb/3/30/MQTT_Command_11.png/600px-MQTT_Command_11.png||height="308" width="600"]]
384
385 MQTT Publish
386
387
388 === 4.4.2 Configure the MQTT Client for Downstream ===
389
390 Below screen shot equal to this subscribe command:
391
392 (% class="box" %)
393 (((
394 mosquitto_sub -h 192.168.199.148 -p 1883 -i dragino-1b7060 -t command.
395 )))
396
397 [[image:https://wiki.dragino.com/images/3/36/MQTT_Command_12.png||height="173" width="579"]]
398
399 MQTT Subscribe
400
401
402 (((
403 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:
404 )))
405
406 [[image:https://wiki.dragino.com/images/thumb/b/b8/MQTT_Command_13.png/600px-MQTT_Command_13.png||height="300" width="600"]]
407
408 LoRa Broadcast parameters.
409
410
411 And below is the subscribe simulation:
412
413 [[image:https://wiki.dragino.com/images/thumb/6/60/MQTT_Command_14.png/600px-MQTT_Command_14.png||height="255" width="600"]]
414
415 downstream simulation
416
417
418 == 4.5 Add LoRa support to communicate with remote sensor ==
419
420 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.
421
422 === 4.5.1 Use LoRa Raw protocol for communication ~-~- For LG01/LG02 ===
423
424 (((
425 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.
426 )))
427
428 (((
429 The example Sketch for LoRa Shield +Arduino is here: [[LoRa_Shield_Sketch_For_MQTT>>url:http://www.dragino.com/downloads/index.php?dir=LoraShield/]]
430 )))
431
432 (((
433 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.
434 )))
435
436 (((
437 What does the Arduino Sketch do? The Arduino Sketch will:
438 )))
439
440 * 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).
441 * Downstream: Listening broadcast message from gateway, and print it in console.
442 * The LoRa parameter settings in Arduino should match the LoRa settings in gateway, as below:
443
444 [[image:https://wiki.dragino.com/images/thumb/3/3b/MQTT_Command_17.png/600px-MQTT_Command_17.png||height="197" width="600"]]
445
446 LoRa Parameter should match
447
448
449 Below is the test result after the Arduino Sketch is running.
450
451 [[image:https://wiki.dragino.com/images/thumb/6/63/MQTT_Command_18.png/600px-MQTT_Command_18.png||height="319" width="600"]]
452
453 Upstream Data Flow
454
455 [[image:https://wiki.dragino.com/images/thumb/1/18/MQTT_Command_19.png/600px-MQTT_Command_19.png||height="309" width="600"]]
456
457 Downstream Data Flow
458
459
460 === 4.5.2 Use LoRaWAN Protocol for communication ~-~- For LG308/LPS8/DLOS8 ===
461
462 (((
463 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.
464 )))
465
466 (((
467 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.
468 (% class="mark" %)**Video Instruction**(%%):[[https:~~/~~/youtu.be/qJTY441-t90>>url:https://youtu.be/qJTY441-t90]]
469 )))
470
471 (((
472 **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.
473 )))
474
475 (((
476 **Step 2**: Make sure your Radio settings match the End Node settings.
477 )))
478
479 [[image:https://wiki.dragino.com/images/thumb/f/f7/LG308_MQTT_5.png/600px-LG308_MQTT_5.png||height="387" width="600"]]
480
481 Use Same Frequency Band as End Node
482
483
484 (((
485 (((
486 **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
487 )))
488 )))
489
490 [[image:https://wiki.dragino.com/images/thumb/8/8d/LG308_MQTT_3.png/600px-LG308_MQTT_3.png||height="385" width="600"]]
491
492 Publish mush use META as data format for LG308
493
494
495 **Step 4**: Map the Device Address to Remote ID in MQTT server.
496
497 [[image:https://wiki.dragino.com/images/thumb/7/7f/LG308_MQTT_4.png/600px-LG308_MQTT_4.png||height="335" width="600"]]
498
499 Map Dev Addr to remote ID
500
501
502 **Step 5: Upstream**: Save the change, we can see the log info via "sytem log", End Node and MQTT Server
503
504 [[image:https://wiki.dragino.com/images/thumb/b/be/LG308_MQTT_6.png/600px-LG308_MQTT_6.png||height="279" width="600"]]
505
506 Upstream Process
507
508 [[image:https://wiki.dragino.com/images/thumb/0/07/LG308_MQTT_6_1.png/600px-LG308_MQTT_6_1.png||height="246" width="600"]]
509
510 Choose ASCII Format
511
512 [[image:https://wiki.dragino.com/images/thumb/a/a3/LG308_MQTT_6_2.png/600px-LG308_MQTT_6_2.png||height="248" width="600"]]
513
514 LHT65 Decoder
515
516
517 **Step 6: Set up subscribe:** Subscribe a topci for downstream.
518
519 [[image:https://wiki.dragino.com/images/thumb/b/b9/LG308_MQTT_7.png/600px-LG308_MQTT_7.png||height="176" width="600"]]
520
521 Subscribe to a topic
522
523
524 **Step 7**: Downstream: Save the change, we can see the log info via "sytem log", End Node and MQTT Server.
525
526 [[image:https://wiki.dragino.com/images/thumb/9/97/LG308_MQTT_8.png/600px-LG308_MQTT_8.png||height="298" width="600"]]
527
528 Downstream Flow
529
530 (% 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]]**
531
532
533 = 5. Example For Different MQTT Servers =
534
535 (% style="width:731.222px" %)
536 |=(% style="width: 270px;" %)(((
537 [[image:https://wiki.dragino.com/images/thumb/7/73/ThingSpeak1.png/200px-ThingSpeak1.png||alt="ThingSpeak1.png" height="114" width="233"]]
538
539 == [[ThingSpeak Server>>url:http://www.thingspeak.com/]] ==
540
541
542 [[Examples>>url:https://wiki.dragino.com/index.php/ThingSpeak_Examples]]
543 )))|=(% style="width: 242px;" %)(((
544 [[image:https://wiki.dragino.com/images/thumb/3/3b/Lewei50.png/200px-Lewei50.png||alt="Lewei50.png" height="65" width="223"]]
545
546
547 == [[乐联网平台>>url:https://www.lewei50.com/]] ==
548
549
550 [[lewei Example>>url:https://wiki.dragino.com/index.php/Lewei_Example_mqtt]]
551 )))|=(% style="width: 214px;" %)(((
552 [[image:https://wiki.dragino.com/images/thumb/a/aa/AWS-IOT.png/200px-AWS-IOT.png||alt="AWS-IOT.png" height="112" width="183"]]
553
554 == [[AWS-IOT>>url:https://aws.amazon.com/cn/iot-platform/how-it-works/]] ==
555
556
557 [[AWS Examples>>url:https://wiki.dragino.com/index.php/MQTT_Forward_to_Amazon_AWS-IOT]]
558 )))
559
560 = 6. How to Debug =
561
562 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.
563
564 = 7. How to ask for Support =
565
566 If a user still not have trouble making it works. please send a mail to support@dragino.com with the below info:
567
568 * Detail of your LoRaWAN end node.
569 * Gateway Model and firmware version
570 * A set of screenshots you configure in the gateway according to our instruction
571 * A full log of "logread -f"