Communication
ESP-GUARDX uses industrial serial communication to exchange data with external field devices, smart component monitors, PLCs, and Modbus-capable instruments. In the current manual, this section mainly covers the RS-485 / Modbus RTU side of the system.
Industrial Protocols
Modbus RTU
Modbus RTU is used for serial communication with devices such as multiphase meters, wellhead pressure and temperature sensors, flow-line measurement devices, smart transformer monitors, and I/O extension modules.
- Connects via RS-485 port
- Configurable baud rate, parity, and stop bits
- Supports per-device register mapping
- Supports read and write access where the connected device allows it
- Shares the same physical RS-485 network shown in the system diagrams
Communication Settings
Communication parameters can be configured in the settings:
| Parameter | Options |
|---|---|
| Modbus RTU | Baud rate, parity, stop bits, slave address |
| UART Sensors | Baud rate, parity, stop bits |
[Screenshot: Communication settings screen]
Where Communication Is Configured
Communication settings appear in more than one place because ESP-GUARDX treats each connected device as part of the configured ESP system.
| Location | What you configure |
|---|---|
| ESP Configurator | Component-level serial line setup for devices such as the VSD, transformers, multiphase meter, wellhead pressure sensor, wellhead temperature sensor, and flow-line rate device. |
| I/O Settings | Digital and analog extension card communication, channel setup, and Modbus register mapping. |
| Register Details | Per-parameter register address, command ID, register type, unit, scale, and access mode. |
Typical Modbus Fields
When matching ESP-GUARDX to an external device, confirm these fields against the device manual:
| Field | Purpose |
|---|---|
| Baud rate | Serial speed. Many default configurations use 9600, but the value must match the connected device. |
| Parity | Error-checking mode. Must match the device setting. |
| Stop bits | Frame timing. Must match the device setting. |
| Slave address | Unique Modbus device ID on the RS-485 bus. |
| Register address | The memory location that contains the measurement or command value. |
| Register type | Coil, discrete input, input register, or holding register, depending on the device map. |
| Scale / UOM | Converts the raw register value into an engineering unit such as psi, degC, bpd, V, or A. |
Troubleshooting
| Symptom | Check |
|---|---|
| No readings from a device | Verify RS-485 A/B wiring, slave address, baud rate, parity, and stop bits. |
| Values update but look wrong | Check register address, register type, scaling, and unit-of-measure. |
| Only one device works on the bus | Look for duplicate slave addresses or incorrect termination. |
| Readings drop in and out | Check cable shielding, grounding, termination, and noise from nearby power wiring. |