rebot-electronic WiFi relays User Manual
- June 7, 2024
- rebot-electronic
Table of Contents
rebot-electronic WiFi relays User Manual
Overview
The ESP32SR88 is a WIFI connected relay module using the popular ESP32.
It provides eight optically isolated inputs and eight volt free contact relay outputs with a current rating of up to 1Amp each.
Power for the board is 12v dc, which can be provided by a standard universal wall power supply. A 1A or greater supply should be selected.
Control Protocols
- Simple plain text commands sent to the module.
- HTML commands
- MQTT
- A built in webpage
WiFi
The ESP32SR88 connects via 2.4GHz WiFi to your network, therefore it must be located in a position where it gets a good WiFi signal. The module should not be enclosed in a metal box/cabinet as this will shield the WiFi signal. You can check the signal level by looking at the RSSI figure which is reported by the ST (STatus) command.
Configuration
The ESP32SR88 is configured by connecting a USB cable to your PC and running a terminal program, PuTTY is a good option if you don’t have any other preferences.
The serial port should be set to 115200 baud, 8 bit, 1 stop, no parity, no flow control.
USB Configuration Commands
ST Status. Return the system status
When the IP address is set to 0.0.0.0 this means that the IP address is being provided by your networks DHCP server. In that case the assigned IP address is also provided, as above.
When the SSID and Password are setup, they will be displayed until the next reset, After that they will only show as ****.
RB ReBoot.
This will restart the module. It may produce a lot of random characters as the ESP32’s boot logging runs at a different baud rate. If it succeeds in connecting to your network it will report the IP address.
WiFi connected.
IP address: 192.168.0.6
IP Sets the modules IP address.
Enter IP followed by the required IP address. Entering address 0.0.0.0 means the IP will be obtained from your networks DHCP server. The new IP address will take effect after the next re-boot.
IP “192.168.0.123” OK. Saved IP Address: 192.168.0.123
SB Sets the SuBnet mask.
SB “255.255.255.0”
OK. Saved Subnet Mask: 255.255.255.0
GW Sets the GateWay address.
This is normally the IP address of your router.
GW “192.168.0.1”
OK. Saved Gateway Address: 192.168.0.1
PD Sets the Primary DNS.
The can be the IP address of your router which will then use your ISP provided DNS. You can also specify the DNS such as 8.8.8.8 for Googles DNS server.
PD “192.168.0.1”
OK. Saved Primary DNS: 192.168.0.1
SD Sets the Secondary DNS.
The can be the IP address of your router which will then use your ISP provided DNS. You can also specify the DNS such as 8.8.4.4 for Googles DNS server. SD “8.8.4.4” OK. Saved Secondary DNS: 8.8.4.4
SS This sets the SSID.
The SSID is the public name of your WIFI network Enter your WIFI’s SSID here.
SS “Devantech”
OK. Saved SSID: Devantech
PW Sets your networks WIFI password.
PW “K]~kCZUVUGA6SG~”
OK. Saved Password: K]~kCZUVUGA6SG~
PA Sets the TCP/IP port number for the ASCII commands.
PA 17126
OK. Saved ASCII port number: 17126
MS Sets the MQTT broker address
MS “192.168.0.121”
OK. Saved MQTT Server: 192.168.0.121
MD Sets the MQTT ID for this module
MS “UniqueModuleName”
OK. Saved MQTT ID: UniqueModuleName
MP Sets the MQTT broker’s port.
Normally, this should be set to 1883.
mp 1883
OK. Saved MQTT port number: 1883
If you are not using MQTT, set the port to 0. This will turn off MQTT, otherwise it will continuously try to connect if there is no MQTT broker.
R1-R8 Sets the MQTT topic this relay is subscribed to.
R3 “Workshop/Heater”
OK. Saved Relay 3 Topic: Workshop/Heater
In use, the payload for relay topics should be a string with the first
character set to 0′ or1′ (ASCII characters 0x31/0x30).
N1-N8 Sets the MQTT topic this Input will publish to.
N2 “Workshop/Heater”
OK. Saved Input 2 Topic: Workshop/Heater
The payload generated for input topics is a string with the first character
set to 1′ if the input is open or unconnected, and0′ if the input pins are
shorted. (ASCII characters 0x31/0x30).
TCP/IP Commands.
The ESP32SR88 has a built in TCP/IP command set which allows you to control the module remotely.
All commands are sent using plain ASCII text. PuTTY is a good cross platform terminal program to use for testing. The TCP/IP port is the one you set-up with the PA command during USB configuration. Do not use port 80 as that is reserved for the HTML commands and Webpage.
SR Set Relay.
This is used to turn a relay on or off
To turn Relay 1 on:
SR 1 1
The first number is the relay number from 1 to 8.
The second number is 1 or 0, on or off.
So turn turn relay 1 off again:
SR 1 0
The command will respond with ok or fail.
SR 1 1
ok
SR 1 6
fail < 6 is not valid, only 1 or 0 for on/off
SR 9 1
fail < relay 9 does not exist.
GR Get Relay.
Will return the state of the relay.
To get the status of relay 6:
GR 6
1
GR 6
0
GR 9
fail < relay 9 does not exist.
GI Get Input.
Will return the status of an input.
GI 2
0 Input 2 is low (Green Led is on)
GI 2
1 Input 2 is high (Green Led is off)
GI 9
fail Only 8 inputs available
AL Get All 8 inputs.
AL 11111011 Here, Input 6 is low, all others are high.
Inputs are numbered from left to right, 1 to 8.
HTML Commands.
There are a set of HTML commands that can be used to control the module.
?Rly3=1 This will turn on relay 3
?Rly3=0 This will turn off relay 3
?Rly3=2 This will toggle relay 3 to the opposite state.
You can enter the commands into a browser immediately after the IP address. http://192.168.0.3/?Rly3=1
This will turn on relay 3. In response the module will return an XML file, which your browser will display.
The XML file is generated after the command has executed, therefore will reflect the new status of the relays.
Webpage
The built in webpage can be used as a remote app to monitor and control the relays. Your can access the page as a default with just the IP address or by specifying index.htm.
The webpage contains the Javascript to send an HTML toggle command, as described in the previous section. It will send the toggle command each time a button is clicked. It then uses the responding XML file to colour the buttons and set the Input buttons to indicate input status.
Schematics
CPU
Power Supply
Relay Outputs
1 of 8 identical circuits shown
The relays are capable of switching up to 1 Amp at 30vdc or 30vac.
Digital Inputs
PCB dimensions
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