diff --git a/source/_components/modbus.markdown b/source/_components/modbus.markdown
index 75581a49746..e08cd84e03a 100644
--- a/source/_components/modbus.markdown
+++ b/source/_components/modbus.markdown
@@ -112,6 +112,13 @@ timeout:
 | ------- | ----------- |
 | write_register | Write register. Requires `unit`, `address` and `value` fields. `value` can be either single value or an array |
 
+#### {% linkable_title Service Data Attributes %}
+
+| Attribute | Description |
+| --------- | ----------- |
+| unit      | Slave address (set to 255 you talk to Modbus via TCP) |
+| address   | Address of the Register (e.g., 138) |
+| value     | An array of 16-bit values. Might need reverse ordering. E.g., to set 0x0004 you might need to set `[4,0]` |
 
 ## {% linkable_title Building on top of Modbus %}