====Modbus RTU/TCP==== {{:projects:modbus.jpg?150|STM32U575}} \\ \\ {{:projects:lm75i2c.jpg?150|LM75 I2C}} \\ \\ {{:projects:max485.jpg?150|MAX485}} \\ \\ {{projects:max485schema.jpg?150}} \\ \\ {{projects:m7rs485.jpg?150|STM32H7A3}} Here are various demos read a values from STM32 devices using `mbpoll' in Linux. ===RTU=== ==RS232== This demo uses the [[:boards:u575|Nucleo U575ZI]] Cortex-M33 development board. It depends on FreeRTOS for demo purposes. The current temperature of an LM75 I2C sensor is read in Q8.8 format. Two TTYs are utilised. The ST-LINK tty is used for the modbus I/O and the other for debug output and was only needed during development so can be ignored. Another demo for the [[boards:stm32f4|STM32 F4 Discovery]] performs modbus rtu over its USB OTG port using the TinyUSB stack. ==RS485== This demo uses the [[:boards:h7a3ziq|Nucleo H7A3ZI-Q]] Cortex-M7 development board. It depends on FreeRTOS for demo purposes. The modbus I/O with this demo uses a MAX485 transceiver and demonstrates how to utilise it. ===TCP=== This demo uses the [[:boards:g491|Nucleo G491RE]] Cortex-M4 development board and an [[:interfaces:enc28j60|ENC28J60]] ethernet MAC/PHY. It depends on [[tools:freertos|FreeRTOS]] with FreeRTOS-PLUS-TCP. VREFINT is read as an input to the STM32 internal ADC. Another demo for the [[:boards:h563zi|Nucleo H563ZI]] utilises its built-in MAC/PHY. ===Install=== ==Firmware== Install mercurial if needed then fetch stm32 microcontroller tests. hg clone http://hg.kewl.org/pub/Archimedes ==Toolchain== Refer to README in the source directory and install dependencies. ==mbpoll== apt install mbpoll ===STM32U575=== cd NUCLEO-U575ZI-Q make program debug ==References== ^Register ^Address ^ Format ^ Mode ^ Comment^ |LM75 temperature | 0x75 | Q8.8 | Read only | Divide by 256.0 to convert to floating point | ==Peek== mbpoll parameter breakdown: * Verbose output: -v * Parity: -P none * Slave address: -a 1 * Reference base zero: -0 * Poll once: -1 * Reference: -r 0x75 * 16-bit register: -t 4:hex * 2 stop bits: -s 2 * 1 register: -c 1 mbpoll -v -P none -a 1 -0 -1 -r 0x75 -t 4:hex -s 2 -c 1 /dev/ttySTLINK3-U575 debug enabled Set rtu parity=none iGetIntList(1) Integer found: 1 iCount=1 Set start reference=117 Set function=4 Set format=hex Set rtu stop bits=2 Set number of values=1 Set mode to RTU for serial port Set device=/dev/ttySTLINK3-U575 mbpoll 1.0-0 - FieldTalk(tm) Modbus(R) Master Simulator Copyright © 2015-2019 Pascal JEAN, https://github.com/epsilonrt/mbpoll This program comes with ABSOLUTELY NO WARRANTY. This is free software, and you are welcome to redistribute it under certain conditions; type 'mbpoll -w' for details. Opening /dev/ttySTLINK3-U575 at 19200 bauds (N, 8, 2) Set response timeout to 1 sec, 0 us Protocol configuration: Modbus RTU Slave configuration...: address = [1] start reference = 117, count = 1 Communication.........: /dev/ttySTLINK3-U575, 19200-8N2 t/o 1.00 s, poll rate 1000 ms Data type.............: 16-bit register, output (holding) register table -- Polling slave 1... [01][03][00][75][00][01][95][D0] Waiting for a confirmation... <01><03><02><1A><00><24> [117]: 0x1A00 The response above is the Q8.8 value of the temperature where 0x1A00 represents 26 degrees Celcius. If an error occurs reading the temperature, the value returned would be -1 (0xFFFF) which is an invalid value and cannot be achieved in normal use. ===STM32G491=== ==peek== mbpoll -v -a 1 -0 -1 -r 0x100 -t 4 -c 1 192.168.0.205 debug enabled iGetIntList(1) Integer found: 1 iCount=1 Set start reference=256 Set function=4 Set number of values=1 Set device=192.168.0.205 mbpoll 1.0-0 - FieldTalk(tm) Modbus(R) Master Simulator Copyright © 2015-2019 Pascal JEAN, https://github.com/epsilonrt/mbpoll This program comes with ABSOLUTELY NO WARRANTY. This is free software, and you are welcome to redistribute it under certain conditions; type 'mbpoll -w' for details. Connecting to [192.168.0.205]:502 Set response timeout to 1 sec, 0 us Protocol configuration: Modbus TCP Slave configuration...: address = [1] start reference = 256, count = 1 Communication.........: 192.168.0.205, port 502, t/o 1.00 s, poll rate 1000 ms Data type.............: 16-bit register, output (holding) register table -- Polling slave 1... [00][01][00][00][00][06][01][03][01][00][00][01] Waiting for a confirmation... <00><01><00><00><00><05><01><03><02><0C> [256]: 3275 ==tcpdump== tcpdump host stm32g4 and port 502 -X tcpdump: verbose output suppressed, use -v[v]... for full protocol decode listening on wlan0, link-type EN10MB (Ethernet), snapshot length 262144 bytes 12:06:19.553003 IP pi1.kewl.org.58674 > stm32g4.kewl.org.502: Flags [S], seq 1040100054, win 64240, options [mss 1460,sackOK,TS val 3692783361 ecr 0,nop,wscale 7], length 0 0x0000: 4510 003c 521f 4000 4006 65ce c0a8 00a1 E.. pi1.kewl.org.58674: Flags [S.], seq 1354047842, ack 1040100055, win 536, options [mss 536], length 0 0x0000: 4510 002c 0014 0000 8006 b7e9 c0a8 00cd E..,............ 0x0010: c0a8 00a1 01f6 e532 50b5 2162 3dfe aad7 .......2P.!b=... 0x0020: 6012 0218 d4c5 0000 0204 0218 0000 `............. 12:06:19.558806 IP pi1.kewl.org.58674 > stm32g4.kewl.org.502: Flags [.], ack 1, win 64240, length 0 0x0000: 4510 0028 5220 4000 4006 65e1 c0a8 00a1 E..(R.@.@.e..... 0x0010: c0a8 00cd e532 01f6 3dfe aad7 50b5 2163 .....2..=...P.!c 0x0020: 5010 faf0 f00d 0000 P....... 12:06:19.579324 IP pi1.kewl.org.58674 > stm32g4.kewl.org.502: Flags [P.], seq 1:13, ack 1, win 64240, length 12 0x0000: 4510 0034 5221 4000 4006 65d4 c0a8 00a1 E..4R!@.@.e..... 0x0010: c0a8 00cd e532 01f6 3dfe aad7 50b5 2163 .....2..=...P.!c 0x0020: 5018 faf0 edee 0000 0001 0000 0006 0103 P............... 0x0030: 0100 0001 .... 12:06:19.580447 IP stm32g4.kewl.org.502 > pi1.kewl.org.58674: Flags [.], ack 13, win 536, length 0 0x0000: 4510 0028 0015 0000 8006 b7ec c0a8 00cd E..(............ 0x0010: c0a8 00a1 01f6 e532 50b5 2163 3dfe aae3 .......2P.!c=... 0x0020: 5010 0218 e8da 0000 0000 0000 0000 P............. 12:06:19.581469 IP stm32g4.kewl.org.502 > pi1.kewl.org.58674: Flags [P.], seq 1:12, ack 13, win 536, length 11 0x0000: 4510 0033 0016 0000 8006 b7e0 c0a8 00cd E..3............ 0x0010: c0a8 00a1 01f6 e532 50b5 2163 3dfe aae3 .......2P.!c=... 0x0020: 5018 0218 1ab2 0000 0001 0000 0005 0103 P............... 0x0030: 020c cb ... 12:06:19.581605 IP pi1.kewl.org.58674 > stm32g4.kewl.org.502: Flags [.], ack 12, win 64229, length 0 0x0000: 4510 0028 5222 4000 4006 65df c0a8 00a1 E..(R"@.@.e..... 0x0010: c0a8 00cd e532 01f6 3dfe aae3 50b5 216e .....2..=...P.!n 0x0020: 5010 fae5 f001 0000 P....... 12:06:19.581868 IP pi1.kewl.org.58674 > stm32g4.kewl.org.502: Flags [F.], seq 13, ack 12, win 64229, length 0 0x0000: 4510 0028 5223 4000 4006 65de c0a8 00a1 E..(R#@.@.e..... 0x0010: c0a8 00cd e532 01f6 3dfe aae3 50b5 216e .....2..=...P.!n 0x0020: 5011 fae5 f000 0000 P....... 12:06:19.582625 IP stm32g4.kewl.org.502 > pi1.kewl.org.58674: Flags [R.], seq 12, ack 13, win 64229, length 0 0x0000: 4510 0028 0017 0000 8006 b7ea c0a8 00cd E..(............ 0x0010: c0a8 00a1 01f6 e532 50b5 216e 3dfe aae3 .......2P.!n=... 0x0020: 5014 fae5 effd 0000 0000 0000 0000 P............. 12:06:19.582921 IP stm32g4.kewl.org.502 > pi1.kewl.org.58674: Flags [R.], seq 12, ack 13, win 64229, length 0 0x0000: 4510 0028 0018 0000 8006 b7e9 c0a8 00cd E..(............ 0x0010: c0a8 00a1 01f6 e532 50b5 216e 3dfe aae3 .......2P.!n=... 0x0020: 5014 fae5 effd 0000 0000 0000 0000 P............. ===Resource === [[https://modbus.org/docs/Modbus_Messaging_Implementation_Guide_V1_0b.pdf|MODBUS TCP]]