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Exo Sense Py Modbus

Modbus RTU Slave and Modbus TCP Server app for Exo Sense Py, configurable via FTP or Web server.

Installation

Just copy all the files in this repo into the Pycom's flash memory.

User guide

Power on Exo Sense Py, the internal LED light will turn on as fixed red. Wait for the LED to turn blue or green.

If green, the module is already configured and ready to process Modbus requests. On the first Modbus request received the LED will go off.

If blue, the module is not configured and is set to access point mode. After some time (see below) the access point will be automatically disabled.

Configuration

All configuration parameters are in the config.py file.

To access this file on the module, enable access point mode and join its WiFi network. Depending on the configuration, a Web server and/or an FTP server will be enabled. Using any Web browser or FTP client application, connect to 192.168.4.1 using the credentials specified in the configuration.

Refer to config.py for the default WiFi, Web and FTP credentials.

Download the configuration file, edit it and re-upload it. If using the Web interface, after the upload, Exo will automatically restart using the new configuration, otherwise, on the next power-on, it will start with the new configuration.

Configure it to work as Modbus RTU slave or Modbus TCP server, by setting MB_RTU_ADDRESS or MB_TCP_IP to a valid value. If both are set, the TCP configuration will be ignored. If neither are, it will boot as not configured and enable the access point at power-on.

When configured as Modbus TCP server, the configuration Web interface and/or FTP server will be available at the configured IP address. If Exo cannot connect to the specified WiFi, after the time specified by the AP_ON_TIMEOUT_SEC configuration parameter, it will go into access point mode.

When configured as RTU slave, to re-enable access point mode, write register 5 via Modbus (see below), or power on the module and wait without making any Modbus requests for the time specified by the AP_ON_TIMEOUT_SEC parameter.

The above access point mode auto-enable routine can be disabled by setting AP_ON_TIMEOUT_SEC to 0.

The access point is automatically disabled after the time specified by AP_ON_TIME_SEC.

LED status table

LED status	Description
Red	Starting up
Green	Ready and waiting for first Modbus request
Off or Blue blink	Running (`HEARTBEAT_LED` config option)
Blue	Access point on
Yellow	Enabling access point
Purple blink	Connecting to WiFi (TCP mode)
Red blink	Not configured and AP timeout expired, reboot to re-enable access point

Modbus registers

Refer to the following table for the list of available registers and corresponding supported Modbus functions.

For the "Functions" column:
1 = Read coils
2 = Read discrete inputs
3 = Read holding registers
4 = Read input registers
5 = Write single coil
6 = Write single register
15 = Write multiple coils
16 = Write multiple registers

Address	R/W	Functions	Size (bits)	Data type	Unit	Description
5	W	5	1	-	-	Write ON (0xFF00) to enable access point mode (RTU only)
101	R	2	1	-	-	Digital input DI1
102	R	2	1	-	-	Digital input DI2
201	R/W	1,5	1	-	-	Digital output DO1
211	W	6	16	unsigned short	ms	DO1 pulse
301	R	4	16	signed short	°C/10	Temperature
302	R	4	16	unsigned short	‰	Relative humidity
303	R	4	16	unsigned short	hPa/10	Atmospheric pressure
304	R	4	16	unsigned short	KΩ	Air resistance (quality indication)
305	R	4	16	unsigned short	lx/10	Light intensity
306	R	4	16	unsigned short	-	Noise intensity
307	R	4	16	unsigned short	-	Peak programme meter simulation on noise value
308	R	4	16	unsigned short	-	IAQ index (see below)
309	R	4	16	signed short	-	IAQ trend: a positive value represents an IAQ improvement, a negative value an IAQ worsening, a value of zero represents a stable IAQ
401	W	6	16	unsigned short	ms	Buzzer beep

IAQ index

IAQ (Indoor Air Quality) index description:

IAQ index	Air Quality
0-50	Good
51-100	Average
101-150	Little bad
151-200	Bad
201-300	Worse
301-500	Very bad