Modbus Controller¶
The modbus_controller component creates a RS485 connection to control a modbus device
The modbus_controller component uses the modbus component
Hardware setup¶
A RS 485 module connected to an ESP32, for example:
See How is this RS485 Module Working? on stackexchange for more details
The controller connects to the UART of the MCU. For ESP32 GPIO PIN 16 to TXD PIN 17 to RXD are the default ports but any other pins can be used as well. 3.3V to VCC and GND to GND.
Note
If you are using an ESP8266, serial logging may cause problems reading from UART. For best results, hardware serial is recommended. Software serial may not be able to read all received data if other components spend a lot of time in the loop().
For hardware serial only a limited set of pins can be used. Either tx_pin: GPIO1 and rx_pin: GPIO3 or tx_pin: GPIO15 and rx_pin: GPIO13.
The disadvantage of using the hardware uart is that you can’t use serial logging because the serial logs would be sent to the modbus device and cause errors.
Serial logging can be disabled by setting baud_rate: 0.
See Logger Component for more details
logger:
level: <level>
baud_rate: 0
Configuration variables:¶
modbus_id (Optional, ID): Manually specify the ID of the modbus hub.
address (Required, ID): The modbus address of the device Specify the modbus device address of the.
command_throttle (Optional, Time): minimum time in between 2 requests to the device. Default is 0ms Because some modbus devices limit the rate of requests the interval between sending requests to the device can be modified.
update_interval (Optional, Time): The interval that the sensors should be checked. Defaults to 60 seconds.
Example¶
The following code create a modbus_controller hub talking to a modbus device at address 1 with 115200 bps
Modbus sensors can be directly defined (inline) under the modbus_controller hub or as standalone components Technically there is no difference between the “inline” and the standard definitions approach.
uart:
id: mod_bus
tx_pin: 17
rx_pin: 16
baud_rate: 115200
stop_bits: 1
modbus:
flow_control_pin: 5
id: modbus1
modbus_controller:
- id: epever
## the Modbus device addr
address: 0x1
modbus_id: modbus1
setup_priority: -10
text_sensor:
- name: "rtc_clock"
platform: modbus_controller
modbus_controller_id: epever
id: rtc_clock
internal: true
register_type: holding
address: 0x9013
register_count: 3
raw_encode: HEXBYTES
response_size: 6
switch:
- platform: modbus_controller
modbus_controller_id: epever
id: reset_to_fabric_default
name: "Reset to Factory Default"
register_type: coil
address: 0x15
bitmask: 1
sensor:
- platform: modbus_controller
modbus_controller_id: epever
name: "Battery Capacity"
id: battery_capacity
register_type: holding
address: 0x9001
unit_of_measurement: "AH"
value_type: U_WORD
Bitmasks¶
Some devices use decimal values in read registers to show multiple binary states occupying only one register address. To decode them, you can use bitmasks according to the table below. The decimal value corresponding to a bit is always double of the previous one in the row. Multiple bits can be represented in a single register by making a sum of all the values corresponding to the bits.
Alarm bit |
Description |
DEC value |
HEX value |
|---|---|---|---|
bit 0 |
Binary Sensor 0 |
1 |
1 |
bit 1 |
Binary Sensor 1 |
2 |
2 |
bit 2 |
Binary Sensor 2 |
4 |
4 |
bit 3 |
Binary Sensor 3 |
8 |
8 |
bit 4 |
Binary Sensor 4 |
16 |
10 |
bit 5 |
Binary Sensor 5 |
32 |
20 |
bit 6 |
Binary Sensor 6 |
64 |
40 |
bit 7 |
Binary Sensor 7 |
128 |
80 |
bit 8 |
Binary Sensor 8 |
256 |
100 |
bit 9 |
Binary Sensor 9 |
512 |
200 |
bit 10 |
Binary Sensor 10 |
1024 |
400 |
bit 11 |
Binary Sensor 11 |
2048 |
800 |
bit 12 |
Binary Sensor 12 |
4096 |
1000 |
bit 13 |
Binary Sensor 13 |
8192 |
2000 |
bit 14 |
Binary Sensor 14 |
16384 |
4000 |
bit 15 |
Binary Sensor 15 |
32768 |
8000 |
For example, when reading register 15, a decimal value of 12288 is the sum of 4096 + 8192, meaning the corresponding bits 12 and 13 are 1, the other bits are 0.
To gather some of these bits as binary sensors in ESPHome, use bitmask:
binary_sensor:
- platform: modbus_controller
modbus_controller_id: ventilation_system
name: Alarm bit0
entity_category: diagnostic
device_class: problem
register_type: read
address: 15
bitmask: 0x1
- platform: modbus_controller
modbus_controller_id: ventilation_system
name: Alarm bit1
entity_category: diagnostic
device_class: problem
register_type: read
address: 15
bitmask: 0x2
- platform: modbus_controller
modbus_controller_id: ventilation_system
name: Alarm bit10
entity_category: diagnostic
device_class: problem
register_type: read
address: 15
bitmask: 0x400
- platform: modbus_controller
modbus_controller_id: ventilation_system
name: Alarm bit15
entity_category: diagnostic
device_class: problem
register_type: read
address: 15
bitmask: 0x8000
Protocol decoding example¶
sensors:
- platform: modbus_controller
modbus_controller_id: epever
id: array_rated_voltage
name: "array_rated_voltage"
address: 0x3000
unit_of_measurement: "V"
register_type: read
value_type: U_WORD
accuracy_decimals: 1
skip_updates: 60
filters:
- multiply: 0.01
- platform: modbus_controller
modbus_controller_id: epever
id: array_rated_current
name: "array_rated_current"
address: 0x3001
unit_of_measurement: "V"
register_type: read
value_type: U_WORD
accuracy_decimals: 2
filters:
- multiply: 0.01
- platform: modbus_controller
modbus_controller_id: epever
id: array_rated_power
name: "array_rated_power"
address: 0x3002
unit_of_measurement: "W"
register_type: read
value_type: U_DWORD_R
accuracy_decimals: 1
filters:
- multiply: 0.01
-platform: modbus_controller
modbus_controller_id: epever
id: battery_rated_voltage
name: "battery_rated_voltage"
address: 0x3004
unit_of_measurement: "V"
register_type: read
value_type: U_WORD
accuracy_decimals: 1
filters:
- multiply: 0.01
- platform: modbus_controller
modbus_controller_id: epever
id: battery_rated_current
name: "battery_rated_current"
address: 0x3005
unit_of_measurement: "A"
register_type: read
value_type: U_WORD
accuracy_decimals: 1
filters:
- multiply: 0.01
- platform: modbus_controller
modbus_controller_id: epever
id: battery_rated_power
name: "battery_rated_power"
address: 0x3006
unit_of_measurement: "W"
register_type: read
value_type: U_DWORD_R
accuracy_decimals: 1
filters:
- multiply: 0.01
- platform: modbus_controller
modbus_controller_id: epever id: charging_mode
name: "charging_mode"
address: 0x3008
unit_of_measurement: ""
register_type: read
value_type: U_WORD
accuracy_decimals: 0
To minimize the required transactions all registers with the same base address are read in one request. The response is mapped to the sensor based on register_count and offset in bytes.
Request
data |
description |
|---|---|
0x1 (01) |
device address |
0x4 (04) |
function code 4 (Read Input Registers) |
0x30 (48) |
start address high byte |
0x0 (00) |
start address low byte |
0x0 (00) |
number of registers to read high byte |
0x9 (09) |
number of registers to read low byte |
0x3f (63) |
crc |
0xc (12) |
crc |
Response
offset |
data |
value (type) |
description |
|---|---|---|---|
H |
0x1 (01) |
device address |
|
H |
0x4 (04) |
function code |
|
H |
0x12 (18) |
byte count |
|
0 |
0x27 (39) |
U_WORD |
array_rated_voltage high byte |
1 |
0x10 (16) |
0x2710 (100000) |
array_rated_voltage low byte |
2 |
0x7 (7) |
U_WORD |
array_rated_current high byte |
3 |
0xd0 (208) |
0x7d0 (2000) |
array_rated_current low byte |
4 |
0xcb (203) |
U_DWORD_R |
array_rated_power high byte of low word |
5 |
0x20 (32) |
spans 2 register |
array_rated_power low byte of low word |
6 |
0x0 (0) |
array_rated_power high byte of high word |
|
7 |
0x0 (0) |
0x0000CB20 (52000) |
array_rated_power low byte of high word |
8 |
0x9 (09) |
U_WORD |
battery_rated_voltage high byte |
9 |
0x60 (96) |
0x960 (2400) |
battery_rated_voltage low byte |
10 |
0x7 (07) |
U_WORD |
battery_rated_current high word |
11 |
0xd0 (208) |
0x7d0 (2000) |
battery_rated_current high word |
12 |
0xcb (203) |
U_DWORD_R |
battery_rated_power high byte of low word |
13 |
0x20 (32) |
spans 2 register |
battery_rated_power low byte of low word |
14 |
0x0 (0) |
battery_rated_power high byte of high word |
|
15 |
0x0 (0) |
0x0000CB20 (52000) |
battery_rated_power low byte of high word |
16 |
0x0 (0) |
U_WORD |
charging_mode high byte |
17 |
0x2 (02) |
0x2 (MPPT) |
charging_mode low byte |
C |
0x2f (47) |
crc |
|
C |
0x31 (49) |
crc |
Note¶
Write support is only implemented for switches and selects. However the C++ code provides the required API to write to a modbus device.
These methods can be called from a lambda.
Here is an example how to set config values to for an EPEVER Trace AN controller. The code synchronizes the localtime of MCU to the epever controller The time is set by writing 12 bytes to register 0x9013. Then battery charge settings are sent.
esphome:
on_boot:
## configure controller settings at setup
## make sure priority is lower than setup_priority of modbus_controller
priority: -100
then:
- lambda: |-
// get local time and sync to controller
time_t now = ::time(nullptr);
struct tm *time_info = ::localtime(&now);
int seconds = time_info->tm_sec;
int minutes = time_info->tm_min;
int hour = time_info->tm_hour;
int day = time_info->tm_mday;
int month = time_info->tm_mon + 1;
int year = time_info->tm_year % 100;
esphome::modbus_controller::ModbusController *controller = id(epever);
// if there is no internet connection localtime returns year 70
if (year != 70) {
// create the payload
std::vector<uint16_t> rtc_data = {uint16_t((minutes << 8) | seconds), uint16_t((day << 8) | hour),
uint16_t((year << 8) | month)};
// Create a modbus command item with the time information as the payload
esphome::modbus_controller::ModbusCommandItem set_rtc_command =
esphome::modbus_controller::ModbusCommandItem::create_write_multiple_command(controller, 0x9013, 3, rtc_data);
// Submit the command to the send queue
epever->queue_command(set_rtc_command);
ESP_LOGI("ModbusLambda", "EPSOLAR RTC set to %02d:%02d:%02d %02d.%02d.%04d", hour, minutes, seconds, day, month,
year + 2000);
}
// Battery settings
// Note: these values are examples only and apply my AGM Battery
std::vector<uint16_t> battery_settings1 = {
0, // 9000 Battery Type 0 = User
0x0073, // 9001 Battery Cap 0x55 == 115AH
0x012C, // 9002 Temp compensation -3V /°C/2V
0x05DC, // 9003 0x5DC == 1500 Over Voltage Disconnect Voltage 15,0
0x058C, // 9004 0x58C == 1480 Charging Limit Voltage 14,8
0x058C, // 9005 Over Voltage Reconnect Voltage 14,8
0x05BF, // 9006 Equalize Charging Voltage 14,6
0x05BE, // 9007 Boost Charging Voltage 14,7
0x0550, // 9008 Float Charging Voltage 13,6
0x0528, // 9009 Boost Reconnect Charging Voltage 13,2
0x04C4, // 900A Low Voltage Reconnect Voltage 12,2
0x04B0, // 900B Under Voltage Warning Reconnect Voltage 12,0
0x04BA, // 900c Under Volt. Warning Volt 12,1
0x04BA, // 900d Low Volt. Disconnect Volt. 11.8
0x04BA // 900E Discharging Limit Voltage 11.8
};
// Boost and equalization periods
std::vector<uint16_t> battery_settings2 = {
0x0000, // 906B Equalize Duration (min.) 0
0x0075 // 906C Boost Duration (aka absorb) 117 mins
};
esphome::modbus_controller::ModbusCommandItem set_battery1_command =
esphome::modbus_controller::ModbusCommandItem::create_write_multiple_command(controller, 0x9000, battery_settings1.size() ,
battery_settings1);
esphome::modbus_controller::ModbusCommandItem set_battery2_command =
esphome::modbus_controller::ModbusCommandItem::create_write_multiple_command(controller, 0x906B, battery_settings3.size(),
battery_settings2);
delay(200) ;
controller->queue_command(set_battery1_command);
delay(200) ;
controller->queue_command(set_battery2_command);
ESP_LOGI("ModbusLambda", "EPSOLAR Battery set");
uart:
id: mod_bus
tx_pin: 19
rx_pin: 18
baud_rate: 115200
stop_bits: 1
modbus:
#flow_control_pin: 23
send_wait_time: 200ms
id: mod_bus_epever
modbus_controller:
- id: epever
## the Modbus device addr
address: 0x1
modbus_id: mod_bus_epever
command_throttle: 0ms
setup_priority: -10
update_interval: ${updates}
sensor:
- platform: modbus_controller
modbus_controller_id: epever
id: array_rated_voltage
name: "array_rated_voltage"
address: 0x3000
unit_of_measurement: "V"
register_type: read
value_type: U_WORD
accuracy_decimals: 1
filters:
- multiply: 0.01
- platform: modbus_controller
modbus_controller_id: epever
id: array_rated_current
name: "array_rated_current"
address: 0x3001
unit_of_measurement: "A"
register_type: read
value_type: U_WORD
accuracy_decimals: 2
filters:
- multiply: 0.01
- platform: modbus_controller
modbus_controller_id: epever
id: array_rated_power
name: "array_rated_power"
address: 0x3002
unit_of_measurement: "W"
register_type: read
value_type: U_DWORD_R
accuracy_decimals: 1
filters:
- multiply: 0.01