What you will achieve
A changing device value updates the same channel’s value, timestamp, and status in a Web table.
Before you begin
- A working installation with project upload.
- A reachable Modbus TCP test device or separately prepared simulator, plus its register map.
01 · Write a test-point sheet
- Record IP, port, Unit ID, function code, address, type, word order, and scale for one readable register.
- For example, raw value 253 scaled by 0.1 gives 25.3 °C. These are illustrative values; use your device map.
- A documented address such as 40001 may differ from a zero-based protocol offset; check the template convention.
Expected result
One unambiguous measurement definition is available.
02 · Configure a line and device
- In the Communicator configuration, create or select a test line and add a device using DrvModbus.
- Choose or edit a template with one read group and set TCP connection, device address, and polling interval.
- Save and upload to the selected instance, then apply the configuration as required. A Modbus slave service is not a replacement for a polling master.
Expected result
Communicator loads the intended device and template.
03 · Verify polling before Web
- Inspect the line/device status and communication log for actual responses.
- Compare the device tag’s value, quality, and timestamp with the device. Resolve polling failures before moving on.
Expected result
The device tag receives valid, regularly updated data.
04 · Map the value to a Server channel
- Create an input channel for the device with the correct type, unit, and display format.
- Map the tag code or tag number, enable the channel, and use an unused channel number.
- Apply scaling at one appropriate layer so the value is not scaled twice.
Expected result
The Server channel matches the device tag’s value, status, and timestamp.
05 · Verify the loop in a table view
- Create a table view containing the channel, register it, assign its object and view permissions, and deploy.
- Open the table in Web and change the test input; compare values and timestamps at both ends.
- Observe one normal update, one disconnected quality state, and successful recovery.
Expected result
The display shows fresh data and correctly distinguishes lost communication.
Troubleshooting
Polling times out
Check network, TCP port, Unit ID, function code, and register range. Ping alone does not validate Modbus.
Device values exist but Web is empty
Check Server current data first, then tag/channel mapping, deployment target, view channel number, and permissions.
Values are huge or have the wrong sign
Check signedness, 16/32-bit type, byte/word order, and duplicated scaling.