Modbus TCP/UDP
Modbus TCP/UDP
The Modbus TCP and Modbus UDP drivers are used to communicate with industrial devices (PLCs, Remote I/O, HMIs, Drives, etc.) that have an Ethernet port, via TCP/IP networks. It is the most widely used Ethernet protocol in the industrial automation field.
Connection Settings
When you select the protocol name in the tree structure (e.g., [1] Network), these settings define how SCADA will reach the target device over the network.
| Parameter | Description | Example Value |
| Ethernet Adapter | Selects which network interface on your computer will be used. If set to “All,” Windows’ default routing table is used. | All |
| IP Address | The IP address of the PLC on the network. | 192.168.0.10 |
| Port | TCP communication port. The default is typically 502. | 502 |
| Delay (ms) | Minimum waiting time between two data requests. Used for balancing network traffic. | 100 |
| Timeout (ms) | Maximum waiting time for a response after a request is sent. If exceeded, a Timeout error occurs. | 250 |
| Retry Count | Number of retries before the system enters the Fault state after a communication error or connection loss. | 3 |
Device Settings
When Device is selected in the tree, this panel is used to configure the Unit ID and data packet settings of the device at the specified IP address.
| Parameter | Description |
| Address | Station Number (Slave ID). Each device on the network must have a unique ID. |
| Symbol | Symbolic name assigned to the device (e.g., Device). |
| Enable | Determines whether the device is active. Conditions can be defined to dynamically enable or disable communication. If multiple conditions are added, the device becomes active if any of them is true. Leave empty to keep the device always active. |
| Byte Ordering | Endianness setting for 32-bit values (Real/Float, DInt). If the numeric values appear incorrect or meaningless, try changing this setting (LittleEndian, BigEndian, Swap Bytes, etc.) to match the device’s data format. |
| Use Func. Code 5 | Checked: Uses FC 05 (Write Single Coil) when writing a single bit.Unchecked: Uses FC 15 (Write Multiple Coils). Older devices may not support FC 15, so this option may need to be enabled. |
| Use Func. Code 6 | Checked: Uses FC 06 (Write Single Register).Unchecked: Uses FC 16 (Write Multiple Registers). |
| Discrete Max. Block | Maximum number of bits (Coils/Inputs) to be read in a single request. Default value 2040 is recommended. Can be reduced if bit addresses are very scattered. |
| Analog Max. Block | Maximum number of registers (Words) to be read in a single request. Modbus standard limits this to 125. |
| Connected | Becomes True when communication with the device is successfully established. |
| Fault | Becomes True when a communication error occurs. |
| Comment | Descriptive note for the device. |
Addressing Table
Wise SCADA uses the standard 5-digit or 6-digit Modbus addressing notation for Modbus TCP and UDP.
| Address Range | Data Type | Description | Function Codes (FC) |
| 000001 – 065536 | Discrete Output | Coils (Bit): Read/write digital outputs/relays. | Read: 01 — Write: 05, 15 |
| 100001 – 165536 | Discrete Input | Contacts (Bit): Read-only digital inputs. | Read: 02 |
| 300001 – 365536 | Analog Input | Input Registers (Word): Read-only 16-bit analog values. | Read: 04 |
| 400001 – 465536 | Analog Output | Holding Registers (Word): Read/write 16-bit memory registers. Most commonly used data area. | Read: 03 — Write: 06, 16 |