| **Parameter** | **Type** | **Description** | **Required** | **Default Value** (when not specified) | **Range** | ||
|---|---|---|---|---|---|---|---|
| TCP | RTU/ASCII | Min | Max | ||||
| name | string | User-friendly name for a device | Yes | Yes | |||
| description | string | Description of a device | No | No | |||
| device\_alias | string | Alphanumeric string to identify a device | Yes | Yes | |||
| enable | boolean | Enabling/disabling of a device | No | No | 1 | 0 | 1 |
| protocol | string | Protocol to be used | Yes | Yes | Modbus RTU, Modbus TCP | ||
| ip | string | The IP address of the TCP slave device | Yes | - | |||
| port | integer | TCP communication port | Yes | - | 502 | ||
| bind\_address | string | The IP address of the network adapter used to connect to the slave device (Default: ”0.0.0.0”) | No | No | 0.0.0.0 | ||
| id | integer | Modbus Slave ID | Yes | Yes | |||
| mode | string | Choosing between RTU (”rtu”), ASCII (”ascii”) and TCP(”tcp”) modes. ASCII is the same as RTU, but with ASCII symbols. | No | No | TCP (for TCP) RTU (for Serial) | rtu, ascii, tcp | |
| timeout\_ms | integer | Response timeout in milliseconds | Yes | Yes | 10000 | ||
| device | string | Communication port (”PORT1”/”PORT2”) | - | Yes | PORT1 | PORT2 | |
| baudrate | integer | Communication speed, baud/s | - | Yes | 9600 | 300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200 | |
| databits | integer | Data bit count for communication | - | Yes | 8 | 6 | 9 |
| stopbits | integer | Stop bit count for communication | - | Yes | 1 | 1 | 2 |
| parity | string | Communication parity option | - | Yes | none | none, even, odd | |
| flowcontrol | string | Number of requests, before the link is considered lost (device status signals are changed) and reconnect attempt will be issued | - | Yes | none | none | |
| scan\_rate\_ms | integer | If provided and positive - all jobs will have similar scan rates - all reads and writes will be executed within this timeframe (parameter scan\_rate\_ms in the Signals tab will be ignored) | Yes | Yes | 300 | ||
| retry\_count | integer | Number of requests, before the link is considered lost (device status signals are changed) and reconnect attempt will be issued | No | No | 3 | ||
| serial\_delay | integer | RS485 delay between read and write operations in milliseconds | - | Yes | 50 | ||
| keep\_alive\_timeout | integer | Time interval for sending a keep-alive packet (in milliseconds) | No | No | 60 | ||
| modbus\_multi\_write | boolean | Use 15/16 functions to write 1 register/coil (Default: 0) | No | No | 0 | 0 | 1 |
| comm\_restart\_delay | integer | Time delay between disconnecting from the slave device and restarting the connection (in milliseconds) (Default: 500) | No | - | 500 | ||
| **Parameter** | **Type** | **Description** | **Required** | **Default Value** (when not specified) | **Range** | ||
|---|---|---|---|---|---|---|---|
| TCP | RTU/ASCII | Min | Max | ||||
| signal\_name | string | User-friendly signal name | Yes | Yes | |||
| device\_alias | string | Alphanumeric string to identify a device | Yes | Yes | |||
| signal\_alias | string | Unique alphanumeric name of the signal to be Yes used | Yes | Yes | |||
| enable | boolean | Enabling/disabling of an individual signal | No | No | 1 | 0 | 1 |
| job\_todo | string | Request to send according to Modbus specification without device address and checksum. This field can be identical on several tags to fetch them in a single request | Yes | Yes | |||
| tag\_job\_todo | string | Similar format to the job\_todo field. Address and length must be a subset of the job field. Defines the individual tag’s register(s) or coil(s). Can be described in HEX or DEC formats | Yes | Yes | |||
| number\_type | string | Type of a number (FLOAT, DOUBLE, DIGITAL, etc.) | Yes | Yes | |||
| log | integer | If the log parameter is 1, the signal will be visible in the events log tab, if 0, signals will not be logged. | No | No | 0 | ||
| pulse\_short\_time\_ms | integer | The time interval for short output pulse to stay active | No | No | 0 | ||
| pulse\_long\_time\_ms | integer | The time interval for a long output pulse to stay active | No | No | 0 | ||
| periodic\_update\_ms | integer | Signal value will be published periodically according to the value set. | No | No | |||
Note: If the number type is more than 16 bits (this means FLOAT, SIGNED32, DOUBLE etc.), modbus multiwrite should be enabled (1).
##### Device status signals Modbus Master has an additional signal which can be configured to show communication status. It is used to indicate if the slave device has disconnected from the master (WCC Lite). To configure such signal for Modbus protocol, job\_todo and tag\_job\_todo fields with string values are required. For Modbus master required parameters for the status signal will be **signal\_name** **device\_alias, signal\_alias, number\_type, job\_todo** and **tag\_job\_todo**. Job\_todo value must be *device\_status* and for tag\_job\_todo there are 4 variations: communication\_status, device\_running, device\_error, uknown\_error. Each signal has 4 possible values and is based on the same logic. If the signal returns the value of 0, it means an unknown error has appeared, 1 – device or protocol connection is on and working properly, 2 – device is off or protocol is disconnected, 3 – error or service is down. Different device vendors can have different implementations of a Modbus protocol stack. A register table can be one of the primary differences. WCC Lite Modbus Master transmits the most significant word (byte) first, however, devices from some vendors might require transmitting the least significant word (byte) first. If that is the case, make sure to switch bytes as needed. To find out more about setting a correct number format, one should consult a section [`number_type`](https://wiki.elseta.com/link/859#bkmrk-number_type-field). Modbus job or tag (as a task to be completed) can be built in two different formats - the user can select a more convenient way for him: - hexadecimal format with every single byte separated by a | symbol. Device address, bytes containing output information and CRC (LRC) bytes should be excluded from the message; - decimal format containing function number, first address and address count, separated by ; symbol. All other information should be excluded from the message; `job_todo` can group several `tag_job_todo`’s. That way one Modbus message can be used to extract several tags. Grouping is accomplished dynamically meaning that if several identical jobs are found, their tags are grouped automatically. #### Debugging a Modbus Master application If the configuration for Modbus Master is set up, a handler for the protocol will start automatically. If the configuration is missing or contains errors, the protocol will not start. It is done intentionally to decrease unnecessary memory usage. Modbus Master command line debugging options `modbus-master ` ``` -h [ –help ] Display help information -V [ –version ] Show version -d