Wiki source code of RS485-LN – RS485 to LoRaWAN Converter

Version 42.2 by Xiaoling on 2022/06/02 16:44

version	line-number	content
3.2	1	(% style="text-align:center" %)
18.2	2	[[image:1653266934636-343.png\|\|height="385" width="385"]]
1.1	3
	4
	5
18.2	6	RS485-LN – RS485 to LoRaWAN Converter User Manual
1.1	7
	8
3.2	9	Table of Contents:
1.1	10
	11
	12
	13
	14
3.2	15	= 1.Introduction =
1.1	16
19.2	17	== 1.1 What is RS485-LN RS485 to LoRaWAN Converter ==
1.1	18
3.2	19	(((
	20	(((
32.3	21	The Dragino RS485-LN is a (% style="color:blue" %)RS485 to LoRaWAN Converter(%%). It converts the RS485 signal into LoRaWAN wireless signal which simplify the IoT installation and reduce the installation/maintaining cost.
3.2	22	)))
2.2	23
3.2	24	(((
32.3	25	RS485-LN allows user to (% style="color:blue" %)monitor / control RS485 devices(%%) and reach extremely long ranges. It provides ultra-long range spread spectrum communication and high interference immunity whilst minimizing current consumption. It targets professional wireless sensor network applications such as irrigation systems, smart metering, smart cities, smartphone detection, building automation, and so on.
3.2	26	)))
2.2	27
3.2	28	(((
32.3	29	(% style="color:blue" %)For data uplink(%%), RS485-LN sends user-defined commands to RS485 devices and gets the return from the RS485 devices. RS485-LN will process these returns according to user-define rules to get the final payload and upload to LoRaWAN server.
3.2	30	)))
2.2	31
3.2	32	(((
32.3	33	(% style="color:blue" %)For data downlink(%%), RS485-LN runs in LoRaWAN Class C. When there downlink commands from LoRaWAN server, RS485-LN will forward the commands from LoRaWAN server to RS485 devices.
32.2	34
32.3	35	(% style="color:blue" %)Demo Dashboard for RS485-LN(%%) connect to two energy meters: [[https:~~/~~/app.datacake.de/dashboard/d/58844a26-378d-4c5a-aaf5-b5b5b153447a>>url:https://app.datacake.de/dashboard/d/58844a26-378d-4c5a-aaf5-b5b5b153447a]]
3.2	36	)))
	37	)))
2.2	38
19.2	39	[[image:1653267211009-519.png\|\|height="419" width="724"]]
2.2	40
32.4	41
3.2	42	== 1.2 Specifications ==
2.2	43
32.6	44
2.2	45	Hardware System:
	46
	47	* STM32L072CZT6 MCU
22.4	48	* SX1276/78 Wireless Chip
2.2	49	* Power Consumption (exclude RS485 device):
19.3	50	** Idle: 32mA@12v
	51	** 20dB Transmit: 65mA@12v
2.2	52
	53	Interface for Model:
	54
19.3	55	* RS485
22.4	56	* Power Input 7~~ 24V DC.
2.2	57
	58	LoRa Spec:
	59
	60	* Frequency Range:
	61	** Band 1 (HF): 862 ~~ 1020 Mhz
	62	** Band 2 (LF): 410 ~~ 528 Mhz
	63	* 168 dB maximum link budget.
	64	* +20 dBm - 100 mW constant RF output vs.
19.3	65	* +14 dBm high efficiency PA.
2.2	66	* Programmable bit rate up to 300 kbps.
	67	* High sensitivity: down to -148 dBm.
	68	* Bullet-proof front end: IIP3 = -12.5 dBm.
	69	* Excellent blocking immunity.
19.3	70	* Low RX current of 10.3 mA, 200 nA register retention.
2.2	71	* Fully integrated synthesizer with a resolution of 61 Hz.
19.3	72	* FSK, GFSK, MSK, GMSK, LoRaTM and OOK modulation.
2.2	73	* Built-in bit synchronizer for clock recovery.
	74	* Preamble detection.
	75	* 127 dB Dynamic Range RSSI.
19.3	76	* Automatic RF Sense and CAD with ultra-fast AFC.
	77	* Packet engine up to 256 bytes with CRC.
2.2	78
3.3	79	== 1.3 Features ==
2.2	80
19.4	81	* LoRaWAN Class A & Class C protocol (default Class C)
2.2	82	* Frequency Bands: CN470/EU433/KR920/US915/EU868/AS923/AU915/IN865/RU864
	83	* AT Commands to change parameters
19.4	84	* Remote configure parameters via LoRa Downlink
2.2	85	* Firmware upgradable via program port
	86	* Support multiply RS485 devices by flexible rules
	87	* Support Modbus protocol
19.4	88	* Support Interrupt uplink (Since hardware version v1.2)
2.2	89
3.3	90	== 1.4 Applications ==
2.2	91
	92	* Smart Buildings & Home Automation
	93	* Logistics and Supply Chain Management
	94	* Smart Metering
	95	* Smart Agriculture
	96	* Smart Cities
	97	* Smart Factory
	98
6.2	99	== 1.5 Firmware Change log ==
2.2	100
19.4	101	[[RS485-LN Image files – Download link and Change log>>url:http://www.dragino.com/downloads/index.php?dir=RS485-LN/]]
2.2	102
32.10	103
4.2	104	== 1.6 Hardware Change log ==
2.2	105
4.2	106	(((
	107	(((
19.4	108	v1.2: Add External Interrupt Pin.
2.2	109
19.4	110	v1.0: Release
32.10	111
	112
4.2	113	)))
	114	)))
2.2	115
20.2	116	= 2. Power ON Device =
2.2	117
6.2	118	(((
20.2	119	The RS485-LN can be powered by 7 ~~ 24V DC power source. Connection as below
2.2	120
20.2	121	* Power Source VIN to RS485-LN VIN+
	122	* Power Source GND to RS485-LN VIN-
2.2	123
20.3	124	(((
20.2	125	Once there is power, the RS485-LN will be on.
20.3	126	)))
2.2	127
20.2	128	[[image:1653268091319-405.png]]
32.11	129
	130
20.2	131	)))
2.2	132
6.2	133	= 3. Operation Mode =
2.2	134
6.2	135	== 3.1 How it works? ==
2.2	136
7.2	137	(((
21.2	138	The RS485-LN is configured as LoRaWAN OTAA Class C mode by default. It has OTAA keys to join network. To connect a local LoRaWAN network, user just need to input the OTAA keys in the network server and power on the RS485-LN. It will auto join the network via OTAA.
32.12	139
	140
7.2	141	)))
2.2	142
7.2	143	== 3.2 Example to join LoRaWAN network ==
2.2	144
6.2	145	Here shows an example for how to join the TTN V3 Network. Below is the network structure, we use [[LG308>>url:http://www.dragino.com/products/lora-lorawan-gateway/item/140-lg308.html]] as LoRaWAN gateway here.
2.2	146
21.2	147	[[image:1653268155545-638.png\|\|height="334" width="724"]]
2.2	148
32.13	149
15.3	150	(((
32.13	151	(((
22.2	152	The RS485-LN in this example connected to two RS485 devices for demonstration, user can connect to other RS485 devices via the same method. The connection is as below:
32.13	153	)))
2.2	154
32.13	155	(((
22.2	156	485A+ and 485B- of the sensor are connected to RS485A and RA485B of RS485-LN respectively.
32.13	157	)))
22.2	158
	159	[[image:1653268227651-549.png\|\|height="592" width="720"]]
	160
15.3	161	(((
22.2	162	The LG308 is already set to connect to [[TTN V3 network >>path:eu1.cloud.thethings.network/]]. So what we need to now is only configure the TTN V3:
15.3	163	)))
2.2	164
15.3	165	(((
22.2	166	Step 1: Create a device in TTN V3 with the OTAA keys from RS485-LN.
15.3	167	)))
2.2	168
15.3	169	(((
22.2	170	Each RS485-LN is shipped with a sticker with unique device EUI:
15.3	171	)))
22.2	172	)))
2.2	173
15.2	174	[[image:1652953462722-299.png]]
2.2	175
15.3	176	(((
22.3	177	(((
2.2	178	User can enter this key in their LoRaWAN Server portal. Below is TTN V3 screen shot:
15.3	179	)))
2.2	180
15.3	181	(((
2.2	182	Add APP EUI in the application.
15.3	183	)))
22.3	184	)))
2.2	185
15.2	186	[[image:image-20220519174512-1.png]]
2.2	187
22.3	188	[[image:image-20220519174512-2.png\|\|height="323" width="720"]]
2.2	189
15.2	190	[[image:image-20220519174512-3.png\|\|height="556" width="724"]]
2.2	191
15.2	192	[[image:image-20220519174512-4.png]]
2.2	193
	194	You can also choose to create the device manually.
	195
15.2	196	[[image:1652953542269-423.png\|\|height="710" width="723"]]
2.2	197
	198	Add APP KEY and DEV EUI
	199
15.2	200	[[image:1652953553383-907.png\|\|height="514" width="724"]]
2.2	201
	202
15.2	203	(((
22.4	204	Step 2: Power on RS485-LN and it will auto join to the TTN V3 network. After join success, it will start to upload message to TTN V3 and user can see in the panel.
15.2	205	)))
2.2	206
15.2	207	[[image:1652953568895-172.png\|\|height="232" width="724"]]
2.2	208
32.14	209
15.5	210	== 3.3 Configure Commands to read data ==
2.2	211
15.5	212	(((
22.4	213	(((
	214	There are plenty of RS485 devices in the market and each device has different command to read the valid data. To support these devices in flexible, RS485-LN supports flexible command set. User can use [[AT Commands>>path:#AT_COMMAND]] or LoRaWAN Downlink Command to configure what commands RS485-LN should send for each sampling and how to handle the return from RS485 devices.
15.5	215	)))
2.2	216
22.4	217	(((
	218	(% style="color:red" %)Note: below description and commands are for firmware version >v1.1, if you have firmware version v1.0. Please check the [[user manual v1.0>>url:http://www.dragino.com/downloads/index.php?dir=RS485-LN/&file=RS485-LN_UserManual_v1.0.1.pdf]] or upgrade the firmware to v1.1
32.15	219
	220
22.4	221	)))
	222	)))
	223
15.5	224	=== 3.3.1 onfigure UART settings for RS485 or TTL communication ===
2.2	225
22.6	226	To use RS485-LN to read data from RS485 sensors, connect the RS485-LN A/B traces to the sensors. And user need to make sure RS485-LN use the match UART setting to access the sensors. The related commands for UART settings are:
2.2	227
32.16	228	(% border="1" style="background-color:#ffffcc; color:green; width:782px" %)
	229	\|(% style="width:128px" %)(((
15.5	230	AT Commands
32.16	231	)))\|(% style="width:305px" %)(((
15.5	232	Description
32.16	233	)))\|(% style="width:346px" %)(((
15.5	234	Example
	235	)))
32.16	236	\|(% style="width:128px" %)(((
15.5	237	AT+BAUDR
32.16	238	)))\|(% style="width:305px" %)(((
15.5	239	Set the baud rate (for RS485 connection). Default Value is: 9600.
32.16	240	)))\|(% style="width:346px" %)(((
15.5	241	(((
2.2	242	AT+BAUDR=9600
15.5	243	)))
2.2	244
15.5	245	(((
2.2	246	Options: (1200,2400,4800,14400,19200,115200)
	247	)))
15.5	248	)))
32.16	249	\|(% style="width:128px" %)(((
15.5	250	AT+PARITY
32.16	251	)))\|(% style="width:305px" %)(((
2.2	252	Set UART parity (for RS485 connection)
32.16	253	)))\|(% style="width:346px" %)(((
15.5	254	(((
2.2	255	AT+PARITY=0
15.5	256	)))
2.2	257
15.5	258	(((
2.2	259	Option: 0: no parity, 1: odd parity, 2: even parity
	260	)))
15.5	261	)))
32.16	262	\|(% style="width:128px" %)(((
15.5	263	AT+STOPBIT
32.16	264	)))\|(% style="width:305px" %)(((
15.5	265	(((
2.2	266	Set serial stopbit (for RS485 connection)
15.5	267	)))
2.2	268
15.5	269	(((
22.6	270
15.5	271	)))
32.16	272	)))\|(% style="width:346px" %)(((
15.5	273	(((
2.2	274	AT+STOPBIT=0 for 1bit
15.5	275	)))
2.2	276
15.5	277	(((
2.2	278	AT+STOPBIT=1 for 1.5 bit
15.5	279	)))
2.2	280
15.5	281	(((
2.2	282	AT+STOPBIT=2 for 2 bits
	283	)))
15.5	284	)))
2.2	285
15.6	286	=== 3.3.2 Configure sensors ===
2.2	287
15.6	288	(((
	289	(((
22.7	290	Some sensors might need to configure before normal operation. User can configure such sensor via PC and RS485 adapter or through RS485-LN AT Commands (% style="color:#4f81bd" %)AT+CFGDEV(%%). Each (% style="color:#4f81bd" %)AT+CFGDEV (%%)equals to send a RS485 command to sensors. This command will only run when user input it and won’t run during each sampling.
15.6	291	)))
22.7	292	)))
2.2	293
15.6	294	(% border="1" style="background-color:#ffffcc; color:green; width:806px" %)
	295	\|AT Commands\|(% style="width:418px" %)Description\|(% style="width:256px" %)Example
	296	\|AT+CFGDEV\|(% style="width:418px" %)(((
2.2	297	This command is used to configure the RS485/TTL devices; they won’t be used during sampling.
	298
15.6	299	AT+CFGDEV=xx xx xx xx xx xx xx xx xx xx xx xx,
2.2	300
15.6	301	mm: 0: no CRC, 1: add CRC-16/MODBUS in the end of this command
	302	)))\|(% style="width:256px" %)AT+CFGDEV=xx xx xx xx xx xx xx xx xx xx xx xx,m
2.2	303
15.6	304	=== 3.3.3 Configure read commands for each sampling ===
2.2	305
15.6	306	(((
35.2	307	During each sampling, we need confirm what commands we need to send to the RS485 sensors to read data. After the RS485 sensors send back the value, it normally include some bytes and we only need a few from them for a shorten payload.
2.2	308
	309	To save the LoRaWAN network bandwidth, we might need to read data from different sensors and combine their valid value into a short payload.
	310
	311	This section describes how to achieve above goals.
	312
35.2	313	During each sampling, the RS485-LN can support 15 commands to read sensors. And combine the return to one or several uplink payloads.
2.2	314
	315
35.2	316	Each RS485 commands include two parts:
2.2	317
35.2	318	~1. What commands RS485-LN will send to the RS485 sensors. There are total 15 commands from AT+COMMAD1, ATCOMMAND2,…, to AT+COMMANDF. All commands are of same grammar.
2.2	319
35.2	320	2. How to get wanted value the from RS485 sensors returns from by 1). There are total 15 AT Commands to handle the return, commands are AT+DATACUT1,AT+DATACUT2,…, AT+DATACUTF corresponding to the commands from 1). All commands are of same grammar.
2.2	321
35.4	322	3. Some RS485 device might has longer delay on reply, so user can use AT+CMDDL to set the timeout for getting reply after the RS485 command is sent. For example AT+CMDDL1=1000 to send the open time to 1000ms
2.2	323
	324
	325	After we got the valid value from each RS485 commands, we need to combine them together with the command AT+DATAUP.
	326
	327
	328	Below are examples for the how above AT Commands works.
	329
	330
35.2	331	AT+COMMANDx : This command will be sent to RS485 devices during each sampling, Max command length is 14 bytes. The grammar is:
	332
	333	(% border="1" style="background-color:#4bacc6; color:white; width:499px" %)
	334	\|(% style="width:496px" %)(((
2.2	335	AT+COMMANDx=xx xx xx xx xx xx xx xx xx xx xx xx,m
	336
	337	xx xx xx xx xx xx xx xx xx xx xx xx: The RS485 command to be sent
	338
	339	m: 0: no CRC, 1: add CRC-16/MODBUS in the end of this command
	340	)))
	341
	342	For example, if we have a RS485 sensor. The command to get sensor value is: 01 03 0B B8 00 02 46 0A. Where 01 03 0B B8 00 02 is the Modbus command to read the register 0B B8 where stored the sensor value. The 46 0A is the CRC-16/MODBUS which calculate manually.
	343
35.2	344	In the RS485-LN, we should use this command AT+COMMAND1=01 03 0B B8 00 02,1 for the same.
2.2	345
	346
	347	AT+DATACUTx : This command defines how to handle the return from AT+COMMANDx, max return length is 45 bytes.
	348
35.2	349	(% border="1" style="background-color:#4bacc6; color:white; width:725px" %)
	350	\|(% style="width:722px" %)(((
2.2	351	AT+DATACUTx=a,b,c
	352
	353	* a: length for the return of AT+COMMAND
	354	* b:1: grab valid value by byte, max 6 bytes. 2: grab valid value by bytes section, max 3 sections.
35.5	355	* c: define the position for valid value.
2.2	356	)))
	357
35.2	358	Examples:
	359
2.2	360	* Grab bytes:
	361
35.2	362	[[image:image-20220602153621-1.png]]
2.2	363
35.2	364
2.2	365	* Grab a section.
	366
35.2	367	[[image:image-20220602153621-2.png]]
2.2	368
35.2	369
2.2	370	* Grab different sections.
	371
35.2	372	[[image:image-20220602153621-3.png]]
35.3	373
	374
35.2	375	)))
2.2	376
29.2	377	=== 3.3.4 Compose the uplink payload ===
2.2	378
29.2	379	(((
2.2	380	Through AT+COMMANDx and AT+DATACUTx we got valid value from each RS485 commands, Assume these valid value are RETURN1, RETURN2, .., to RETURNx. The next step is how to compose the LoRa Uplink Payload by these RETURNs. The command is AT+DATAUP.
35.5	381
	382
29.2	383	)))
2.2	384
29.2	385	(((
35.5	386	(% style="color:#037691" %)Examples: AT+DATAUP=0
	387
	388
29.2	389	)))
2.2	390
29.2	391	(((
	392	Compose the uplink payload with value returns in sequence and send with (% style="color:red" %)A SIGNLE UPLINK.
	393	)))
2.2	394
29.2	395	(((
2.2	396	Final Payload is
29.2	397	)))
2.2	398
29.2	399	(((
	400	(% style="color:#4f81bd" %)Battery Info+PAYVER + VALID Value from RETURN1 + Valid Value from RETURN2 + … + RETURNx
	401	)))
2.2	402
29.2	403	(((
2.2	404	Where PAYVER is defined by AT+PAYVER, below is an example screen shot.
29.2	405	)))
2.2	406
29.3	407	[[image:1653269759169-150.png\|\|height="513" width="716"]]
2.2	408
35.5	409
35.6	410	(% style="color:#037691" %)Examples: AT+DATAUP=1
2.2	411
35.5	412
30.2	413	Compose the uplink payload with value returns in sequence and send with (% style="color:red" %)Multiply UPLINKs.
2.2	414
	415	Final Payload is
	416
30.2	417	(% style="color:#4f81bd" %)Battery Info+PAYVER + PAYLOAD COUNT + PAYLOAD# + DATA
2.2	418
36.2	419	1. PAYVER: Defined by AT+PAYVER
	420	1. PAYLOAD COUNT: Total how many uplinks of this sampling.
	421	1. PAYLOAD#: Number of this uplink. (from 0,1,2,3…,to PAYLOAD COUNT)
	422	1. DATA: Valid value: max 8 bytes for each uplink so each uplink <= 11 bytes. For the last uplink, DATA will might less than 8 bytes
2.2	423
36.2	424	[[image:image-20220602155039-4.png]]
2.2	425
	426
36.2	427	So totally there will be 3 uplinks for this sampling, each uplink include 8 bytes DATA
2.2	428
36.2	429	DATA1=RETURN1 Valid Value + the first two of Valid value of RETURN10= 20 20 0a 33 90 41 02 aa
2.2	430
36.2	431	DATA2=3^^rd^^ ~~ 10^^th^^ byte of Valid value of RETURN10= 05 81 0a 20 20 20 20 2d
2.2	432
36.2	433	DATA3=the rest of Valid value of RETURN10= 30
2.2	434
36.2	435
	436	(% style="color:red" %)Notice: In firmware v1.3, the Max bytes has been changed according to the max bytes in different Frequency Bands for lowest SF. As below:
	437
	438	~* For AU915/AS923 bands, if UplinkDwell time=0, max 51 bytes for each uplink.
	439
	440	* For AU915/AS923 bands, if UplinkDwell time=0, max 11 bytes for each uplink.
	441
	442	* For US915 band, max 11 bytes for each uplink.
	443
	444	~* For all other bands: max 51 bytes for each uplink.
	445
	446
2.2	447	Below are the uplink payloads:
	448
37.2	449	[[image:1654157178836-407.png]]
2.2	450
	451
31.3	452	=== 3.3.5 Uplink on demand ===
2.2	453
37.4	454	Except uplink periodically, RS485-LN is able to uplink on demand. The server send downlink command to RS485-LN and RS485 will uplink data base on the command.
2.2	455
	456	Downlink control command:
	457
37.4	458	0x08 command: Poll an uplink with current command set in RS485-LN.
2.2	459
37.4	460	0xA8 command: Send a command to RS485-LN and uplink the output from sensors.
2.2	461
	462
	463
38.2	464	=== 3.3.6 Uplink on Interrupt ===
2.2	465
38.2	466	RS485-LN support external Interrupt uplink since hardware v1.2 release.
2.2	467
38.2	468	[[image:1654157342174-798.png]]
2.2	469
38.2	470	Connect the Interrupt pin to RS485-LN INT port and connect the GND pin to V- port. When there is a high voltage (Max 24v) on INT pin. Device will send an uplink packet.
2.2	471
	472
38.4	473	== 3.4 Uplink Payload ==
2.2	474
38.4	475	(% border="1" style="background-color:#4bacc6; color:white; width:734px" %)
	476	\|Size(bytes)\|(% style="width:120px" %)2\|(% style="width:116px" %)1\|(% style="width:386px" %)Length depends on the return from the commands
	477	\|Value\|(% style="width:120px" %)(((
2.2	478	Battery(mV)
	479
	480	&
	481
	482	Interrupt _Flag
38.4	483	)))\|(% style="width:116px" %)(((
2.2	484	PAYLOAD_VER
	485
	486
38.4	487	)))\|(% style="width:386px" %)If the valid payload is too long and exceed the maximum support payload length in server, server will show payload not provided in the LoRaWAN server.
2.2	488
	489	Below is the decoder for the first 3 bytes. The rest bytes are dynamic depends on different RS485 sensors.
	490
	491
38.4	492	== 3.5 Configure RS485-BL via AT or Downlink ==
2.2	493
38.4	494	User can configure RS485-LN via AT Commands or LoRaWAN Downlink Commands
2.2	495
38.4	496	There are two kinds of Commands:
2.2	497
38.4	498	* (% style="color:#4f81bd" %)Common Commands(%%): They should be available for each sensor, such as: change uplink interval, reset device. For firmware v1.3, user can find what common commands it supports: [[End Device AT Commands and Downlink Command>>doc:Main.End Device AT Commands and Downlink Command.WebHome]]
2.2	499
38.4	500	* (% style="color:#4f81bd" %)Sensor Related Commands(%%): These commands are special designed for RS485-LN. User can see these commands below:
2.2	501
41.7	502
38.4	503	=== 3.5.1 Common Commands ===
2.2	504
38.4	505	They should be available for each of Dragino Sensors, such as: change uplink interval, reset device. For firmware v1.3, user can find what common commands it supports: [[End Device AT Commands and Downlink Command>>doc:Main.End Device AT Commands and Downlink Command.WebHome]]
2.2	506
	507
41.1	508	=== 3.5.2 Sensor related commands ===
2.2	509
41.1	510	Response feature is added to the server's downlink, a special package with a FPort of 200 will be uploaded immediately after receiving the data sent by the server.
2.2	511
41.1	512	[[image:image-20220602163333-5.png\|\|height="263" width="1160"]]
2.2	513
41.1	514	The first byte of this package represents whether the configuration is successful, 00 represents failure, 01 represents success. Except for the first byte, the other is the previous downlink. (All commands except A8 type commands are applicable)
2.2	515
	516
42.2	517	=== 3.5.3 Sensor related commands ===
2.2	518
41.1	519	==== ====
2.2	520
42.2	521	==== RS485 Debug Command ====
	522
	523	This command is used to configure the RS485 devices; they won’t be used during sampling.
	524
	525	* AT Command
	526
	527	(% class="box infomessage" %)
	528	(((
	529	AT+CFGDEV=xx xx xx xx xx xx xx xx xx xx xx xx,m
	530	)))
	531
	532	m: 0: no CRC, 1: add CRC-16/MODBUS in the end of this command
	533
	534	* Downlink Payload
	535
	536	Format: A8 MM NN XX XX XX XX YY
	537
	538	Where:
	539
	540	* MM: 1: add CRC-16/MODBUS ; 0: no CRC
	541	* NN: The length of RS485 command
	542	* XX XX XX XX: RS485 command total NN bytes
	543	* YY: How many bytes will be uplink from the return of this RS485 command,
	544	** if YY=0, RS485-LN will execute the downlink command without uplink;
	545	** if YY>0, RS485-LN will uplink total YY bytes from the output of this RS485 command; Fport=200
	546	** if YY=FF, RS485-LN will uplink RS485 output with the downlink command content; Fport=200.
	547
	548
	549	Example 1 ~-~-> Configure without ask for uplink (YY=0)
	550
	551	To connect a Modbus Alarm with below commands.
	552
	553	* The command to active alarm is: 0A 05 00 04 00 01 4C B0. Where 0A 05 00 04 00 01 is the Modbus command to read the register 00 40 where stored the DI status. The 4C B0 is the CRC-16/MODBUS which calculate manually.
	554
	555	* The command to deactivate alarm is: 0A 05 00 04 00 00 8D 70. Where 0A 05 00 04 00 00 is the Modbus command to read the register 00 40 where stored the DI status. The 8D 70 is the CRC-16/MODBUS which calculate manually.
	556
	557	So if user want to use downlink command to control to RS485 Alarm, he can use:
	558
	559	(% style="color:#4f81bd" %)A8 01 06 0A 05 00 04 00 01 00(%%): to activate the RS485 Alarm
	560
	561	(% style="color:#4f81bd" %)A8 01 06 0A 05 00 04 00 00 00(%%): to deactivate the RS485 Alarm
	562
	563	A8 is type code and 01 means add CRC-16/MODBUS at the end, the 3^^rd^^ byte is 06, means the next 6 bytes are the command to be sent to the RS485 network, the final byte 00 means this command don’t need to acquire output.
	564
	565
	566	Example 2 ~-~-> Configure with requesting uplink and original downlink command (YY=FF)
	567
	568	User in IoT server send a downlink command: (% style="color:#4f81bd" %)A8 01 06 0A 08 00 04 00 01 YY
	569
	570
	571	RS485-LN got this downlink command and send (% style="color:#4f81bd" %)0A 08 00 04 00 01 (%%)to Modbus network. One of the RS485 sensor in the network send back Modbus reply 0A 08 00 04 00 00. RS485-LN get this reply and combine with the original downlink command and uplink. The uplink message is:
	572
	573	A8 (% style="color:#4f81bd" %)0A 08 00 04 00 (% style="color:red" %)01 06 (% style="color:green" %)0A 08 00 04 00 00
	574
	575	[[image:1654159460680-153.png]]
	576
41.1	577	==== ====

Wiki source code of RS485-LN – RS485 to LoRaWAN Converter

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