Set up registers

A register on the page of a Modbus device applies only to that Modbus device. The template you used to add the Modbus device does not change. After every change, the portal sends the new settings to the gateway. To use the same registers on more Modbus devices, follow Create a custom template.

What you need

• The role Owner, Admin or Technician in your organisation.
• A Modbus device on the gateway, added as described in Add Modbus devices.
• The register map from the manual of the Modbus device. The course explains how to read a register map.

Open the Modbus device

The registers of a Modbus device are on a page of their own.

1. Open the gateway list

   Open Gateways in the menu.

2. Open the gateway

   Click the gateway the Modbus device is connected to.

3. Open the Modbus device

   Under Modbus devices, click the Modbus device. The page Modbus apparaat (Modbus device) opens with the list of registers.

Add a register

Loading the walkthrough.

After these steps, the gateway reads the new register.

1. Open the window

   Click Register toevoegen (Add register).

2. Enter the name

   In Naam (Name), enter the name that should appear with the value, such as Voltage L1.

3. Choose the function

   In Functie (Function), choose the function from the manual, Read holding registers (3) or Read input registers (4).

4. Enter the address

   In Adres (Address), enter the register address, counted from 0.

5. Choose the data type

   In Datatype (Data type), choose the type from the manual.

6. Choose the byte order

   If the type is int32, uint32 or float32, choose the order from the manual in Byte-volgorde (Byte order). If the manual gives none, leave ABCD (1,2,3,4) selected.

7. Enter the unit

   In Eenheid (Unit), enter the unit, such as V or kWh.

8. Enter the scale

   If the manual gives a factor, enter it in Schaal (x) (Scale). Otherwise leave 1.

9. Choose the access

   To control the register from the portal, choose Lezen + schrijven (Read and write) in Toegang (Access).

10. Save the register

    Click Toevoegen (Add). The register appears in the list. As soon as the gateway has read it, the value appears in the column Laatste waarde (Last value).

Choose the function code

The function determines which kind of register the gateway requests. The list in Functie shows English names, with the number of the function code in brackets. A new register is set to Read input registers (4).

The table shows which function belongs to which register in the manual.

For a register, choose one of these two functions. The other functions in the list are for coils or for writing.

A register that you want to control also gets Read holding registers (3). An input register can only be read. The portal chooses the write function itself. A 16-bit register gets function code 6, a 32-bit register function code 16.

Determine the register address

The portal counts register addresses from 0, as they appear in the Modbus message. The field Adres does not convert anything. If the manual gives numbers such as 30001 or 40001, convert them with Enter a register address from the manual.

A 32-bit value takes up two registers. If such values follow each other, their addresses are two apart, such as 0, 2 and 4. Each address occurs once per Modbus device, also with a different function. If the address already exists, the portal reports Dit adres bestaat al op dit apparaat (This address already exists on this device).

The register address is separate from the slave address or unit ID. Set those as described in Set the address and connection of a Modbus device.

Choose the data type and byte order

The gateway reads five data types. Do not choose any other type from the list in Datatype. The gateway reads any other type as float32 over two registers, and then the value is wrong.

The table shows how many registers each type takes up and what kind of number it holds.

For int32, uint32 and float32, the field Byte-volgorde appears in the window. It states the order in which the Modbus device sends the four bytes. If you select Toepassen op alle registers van dit Modbus apparaat (Apply to all registers of this Modbus device), all 32-bit registers of this Modbus device get the same order. How to find the right order is described in Set the byte order and scale factor.

If a register gives an impossible number, see Values are wrong.

Set the unit and scale

The name and the unit appear next to the value on the gateway page and in Trends. In an alert, the unit appears after the value. If the unit contains kWh, the gateway page gets the tab Tariff. What you set there is described in Set up peak and off-peak tariffs per kWh meter.

The portal shows the value that was read, multiplied by Schaal (x). If the gateway reads 2314 and the scale is 0.1, the portal shows 231.4. Alert rules and automations calculate with that result. More examples are in Set the byte order and scale factor.

Make a register writable

A new register is set to Alleen lezen (Read only). A register that you want to control from the portal, such as a setpoint, you set to Lezen + schrijven in Toegang. The register then gets the label RW in the list, and the gateway page gets the tab Control.

Sending a value works only when control is switched on for the gateway. Control is off by default. How to request it is described in Control registers from the portal.

Change a register

You change a register in the same window in which you add it.

1. Open the register

   On the right in the row of the register, click the pencil (Register bewerken, Edit register). The window shows the same fields as when adding.

2. Adjust the fields

   Change the fields that need to change.

3. Save the change

   Click Opslaan (Save). The portal sends the new setting to the gateway.

Delete a register

The gateway no longer reads a register that you delete.

1. Start deleting

   On the right in the row of the register, click the bin (Register verwijderen, Delete register).

2. Confirm the deletion

   Click Bevestigen (Confirm). The register disappears from the list.