Defining a Custom RTU Field
Custom fields must be manually entered into the Modbus map along with their Modbus address and field type. As each field is added into the Modbus map, Profile™ intelligently adapts to make the data entry process as easy as possible.
Specify the fields as follows:
| Field | Description |
| Modbus Address | This is the Modbus address in the RTU that Profile™ must poll to obtain the data. Although a Modbus field must have a unique Modbus addresses, the same Modbus address can appear on different data maps. eg Modbus Address 7000 can appear on both the coil data map and the holding register map. The Modbus address field will automatically increment as fields are added. |
| Data Map | Each field must be assigned to a data map either holding registers, coils, inputs or input registers. |
| Full Field Name | This is the name of the field as used by Profile™. The field should be entered in verbose user-friendly text eg "Stream 1 Temperature High Limit" rather than "STR01 Temp HiLim". Entering the field names properly will help later on when building the screens and reports. |
| Alarm | Setting this checkbox indicates that any non-zero value for the field should cause an alarm to occur. The name of the alarm defaults to the field name. |
| Field Type | Field types define all the field information including 'Data Type', 'Number of Bits', 'Number of Bytes', 'Number of Registers, Reverse Byte Order', 'Reverse Register Order' and 'Signed'. The 'Field Type' popup menu will learn new data types as they are entered. To start with the field type will start off as "Custom". As new fields are entered the list of field types will automatically be updated. To edit a field type once it has been defined, first select the field type from the 'Field Type' popup menu and then click the 'Edit' button. Editing a field type will not affect any other fields using that field type. To add a new field type once the first field type has been added, select "Custom" from the 'Field Type' popup menu. |
| Data Type | This is the data type of the field in the RTU such as "Integer", "Float" or "Double" etc. Choices for the next few options in this section will vary depending on the type of field selected. |
| Number of Bits | How many bits to use for the register. This is only used for integer, floats or doubles. |
| Number of Bytes | How many bytes to use for the register. This is only used for strings. |
| Number of Registers | How many registers to use for the Modbus address. This is normally set to 1. |
| Reverse Byte Order | This checkbox indicates whether the bytes in the register should be reversed. The bytes are not normally reversed. |
| Reverse Register Order | This checkbox indicates whether the register order should be reversed. The registers are not normally reversed. |
| Signed | This checkbox indicates whether the integer should be signed or unsigned? It only applies to integer fields. |
| Constant Table | Constant tables allow text strings to be assigned to numeric values. For more information on setting up constant tables see the Constant Table section. |
| Units | The unit type field defines the units that should be used with this field. For instance, a unit type for "Pressure" can be setup with units "barg". For more information on setting up units see the Units section. |
| Security Level | The security level determines the level of access required by a user before they can edit a field. Most RTUs require that a lower security level needs a higher the level of access to edit the field and vice versa. A security level of 0 means that the field can never be edited. Field security levels correspond to the security level user privileges in the user screen. |
| Read Formula | This is the formula used to turn the value taken from the RTU into a more readable format. eg if an RTU stores a decimal value with 2dps as an integer ie 123.45 = 12345, it must be divided by 100 before it can be displayed. For more information on setting up formulas see the Formula section. |
| Write Formula | This is the opposite of the Read Formula. The write formula will take the readable format and convert into the RTU format when writing the value back to the RTU. Using the example above; if the user writes the value 543.21 into the field it must be first converted back into an integer ie 54321 before it is sent to the RTU. For more information on setting up formulas see the Formula section. |
Once the field has been entered:
- Click the 'Save' button to save the field and return to the fields list
- Click the 'Save and Next' button to save the field and go on to create the next one. The newly created field will automatically inherit the previous field's settings although the Modbus address will be incremented by the value specified in the number of registers field.
- Click the 'Cancel' button to reject the changes made.
Profile™ Configuration Manual