Modbus Master Specification
Protocol
- TCP
- Serial Port : RTU / ASCII
Function Call
- 01 Read Coils
- 02 Read Discrete Inputs
- 03 Read Holding Registers
- 04 Read Input Registers
- 05 Write Single Coil
- 06 Write Single Register
- 15 Write Multiple Coils
- 16 Write Multiple Registers
- 23 Read/Write Multiple Registers
Data Trigger by
- Cyclic / Data Change
Endian Swap
- None / Byte / Word / Byte and Word
Data Scaling
- None / Slop-intercept / Point-slope
Tag Data Type
- raw / boolean / int16 / int32 / int64 / uint16 / uint32 / uint64 / float / double / string
Web UI, RESTful API and Remote Management
Modbus Master application allows you to manage settings in variable ways.
| Feature | Web GUI | RESTful API | Azure Direct Method | MQTT Topic |
|---|---|---|---|---|
| Start/Stop Modbus Master App | O | O | O | O |
| Create slave device - TCP / Serial | O | O | O | O |
| Enable/Disable slave device | O | O | O | O |
| Setting TCP slave device parameters | O | O | O | |
| Setting Serial slave device parameters | O | O | O | O |
| Delete slave device | O | O | O | O |
| Create command by function call | O | O | O | O |
| Create tag associated with command | O | O | O | O |
| Apply endian swap on tag data | O | O | O | O |
| Apply data scaling on tag data | O | O | O | O |
| Update/Delete command | O | O | O | O |
| Update data trigger mode | O | O | O | |
| Import/Export commands as CSV file | O | O | ||
| Import/Export Modbus configuration as CSV file | O | O | ||
| Enable/Disable slave device fail event | O | O | O | O |
| Enable/Disable function call fail event | O | O | O | O |
Please refer to ThingsPro Edge V2.0.0 Restful API
limitation and constrain on device UC-8112A-ME
| Item | Max Value | Note |
|---|---|---|
| Max Serial Slave Device # | 31 | Able to create max 31 serial slave device. |
| Max TCP Slave Device # | 32 | Able to create max 32 TCP slave device. |
| Max Command # | 2048 | Support max 2048 commands across all slave devices. |
| Max Tag # | 2048 | Support max 2048 tags across all commands. |
| Max Command # in a Serial Port | 128 | Support max 128 commands for a serial slave device. |
| Max Command # in a TCP Port | 2048 | Support max 2048 commands for a TCP slave device. |
Modbus Master application support big integer range is:
| Data Type | Min | Max |
|---|---|---|
| Int64 | -922337203685477 | 922337203685477 |
| Unsigned int64 | 0 | 1,844,674,407,370,954 |
Performance benchmark on device UC-8112A-ME.
Environments:
- Running period: 15 minutes
- Slave device: one TCP slave device, two serial slave devices
- Others application: No
| Tags # | Polling Interval (ms) | 1 mins | 5 mins | 15 mins |
|---|---|---|---|---|
| 50 | 1000 | 0.58 | 0.53 | 0.48 |
| 100 | 1000 | 0.81 | 0.77 | 0.62 |
| 150 | 1000 | 0.58 | 0.54 | 0.55 |
| 200 | 1000 | 0.77 | 0.92 | 0.8 |
| 250 | 1000 | 0.83 | 0.82 | 0.85 |
| 300 | 1000 | 2.03 | 1.39 | 1.13 |
The result represents: the UC-8112A-ME gateway device is capable of fetching 250 tags per second over the Modbus protocol.
Last updated on 2022-05-04 by Aeluin Chen (陳映攸)