ComWinTop CWT-THxxS Series - temperature and humidity sensor

Description

• Device class: RS485 temperature and relative humidity sensor
• Brand: ComWinTop
• Name in My Devices: ComWinTop CWT-THxxS Series
• Model: CWT-TH03S-H, the only model of the series in the device list
• Temperature range: -40 °C to +120 °C, accuracy ±0.5 °C
• Humidity range: 0 %RH to 100 %RH, accuracy ±5 %RH
• Model identity: the label on the probe only
• Serial number: typed in when you add the sensor
• Supply: 5 VDC to 30 VDC

LoggerV Connection

• Ethernet: a Modbus TCP to RTU gateway only. Not tested.
• Factory serial settings: 4800 baud, 8 data bits, no parity, 1 stop bit
• Baudrate options in the app: 1200, 2400, 4800, 9600, 19200, 38400, 57600 and 115200. The CWT-THxxS manual lists only 2400, 4800 and 9600 for the sensor.
• Factory Modbus address: 1
• Maximum RS485 distance: up to 800 m

Plant Control Functions

• Monitoring only: no commands

Recorded Data

• Read interval: 5 seconds, one read for the two values
• Logged values: the average, the highest and the lowest value of each log interval
• Charts: Device Historical Analytics

Wiring

The Add-Device wizard makes the connection diagrams. See How to add a device in myPower24. The Solar MD connection guide for this sensor is below.

• LoggerV port: RS485-1, RJ45
• RJ45 crimp: T568B pinout of the ANSI/TIA-568-E standard
• RJ45 pin 4: RS485 B+
• RJ45 pin 5: RS485 A-
• Termination: a 120 Ohm RJ45 termination resistor in the second RS485-1 socket of the LoggerV
• Supply: the 24 VDC rail and ground of the LoggerV
• Sensor leads, units supplied with the LoggerV: blue RS485 B, purple RS485 A, orange supply positive, black supply negative
• Sensor leads, units from other suppliers: blue RS485 B, yellow or green RS485 A, brown supply positive, black supply negative
• Other sensor on the drawing: the DONGKER XY-MD02, factory setting 9600 baud

Setup

1. Connect the sensor as the diagram from the wizard shows. Connect the RS485 pair, the supply and ground, and the termination resistor.
2. Add the device on the LoggerV. See How to add a device in myPower24.
3. Set the port Bus Speed to the baud rate of the sensor. A new sensor uses 4800 baud.
4. Type the Modbus address of the sensor in Modbus Slave ID:.
5. Type the number from the unit label, or a site asset number, in Serial Number:. The limit is 50 characters.
6. Click Try to connect.
7. If more than one sensor is on the RS485 line, give each sensor a different address. Set Settings > Communication Settings > Slave ID to a value from 1 to 254.
8. Open Actual Values. Make sure that Temperature and Humidity change with the conditions at the probe.

The serial number is the permanent identity of the sensor on the platform. When you change Slave ID, the sensor moves to the new address immediately and the LoggerV follows it. You do not add the sensor again.

Device Page

• Actual Values (opens first): Measurements card, with Temperature in °C and Humidity in %RH, to one decimal place. Communication card, with Slave ID and Baudrate as read-only values.
• Settings: Communication Settings, with Slave ID and Baudrate
• Healthy link: Temperature and Humidity change with the conditions at the probe
• Baudrate on a healthy link: a rate label, for example 4800bps
• Start-up value: 0.0 for Temperature and Humidity. It is not a reading.

Troubleshooting

• "Failed to scan ID (device did not respond to all register groups)": the sensor did not reply, so the LoggerV did not add it. Make sure that RS485 A and B are not swapped. Make sure that the port Bus Speed and the sensor baud rate are the same. Then examine the address. The same message shows when a different device replies at that address.
• "Serial Number required. Please provide serial number": the Serial Number field is empty. Type a serial number, then click Try to connect again.
• The sensor stops after a period of correct operation: examine the bus. If the termination resistor is missing, install it. Make sure that no other device uses the same Slave ID. Make sure that all devices on the line use the same baud rate.

Permissions

• See the device page and the recorded data: all access levels
• Change Slave ID and Baudrate: Editor, Installer or Full control
• With Viewer only: the device page shows View-only on this site.
• About the levels: see Access levels field definitions

Tips and Gotchas

• Two sensors on one line: connect and address one sensor at a time. Two sensors at the same address reply at the same time. Thus the scan finds no sensor.
• Serial numbers: before you add a batch, select one source for all serial numbers: the unit label or a site asset number. The platform accepts the same serial number two times.
• Calibration: the sensor has a temperature offset and a humidity offset. The device page does not show them. Use a Modbus tool to change them.
• Unknown address: with only one sensor on the line, a Modbus tool reads the address back from the RS485 broadcast address.