Digital input indications are mirrored on several Modbus memory areas. Indications can be accessed in Communication Management in PCM600, under tabs: 1X – discrete inputs, 0X – read-only coils, 3X – input registers and 4X – holding registers. Digital inputs are read-only objects. Writing to the defined 0X and 4X addresses results in an exception response.
The bit address field shows the 1X and 0X Modbus memory addresses on which the data occur as default. The Modbus register address and bit within the register are shown under the 3X and 4X register views. The address field may also be empty, meaning that the object is not located in the Modbus memory at all as default. The indication objects can be taken into use in the user-definable area.
Modbus Communication Management shows only active data objects, that is, the objects that are available in the functions that are activated in the relay configuration.
| Setting column | Alternatives | Description |
|---|---|---|
| Bit address | Not adjustable | The 0x and 1x bit Modbus memory map address where the object resides as default. If the field is empty, the object is not visible in the Modbus memory map as default. The object can always be further mapped into the user-definable area. |
| Data category | None | Point does not belong to any user-definable data category. |
| 1...16 | Point belongs to data category number N. If any object belonging to this category changes its value, bit (N-1) in SSR3 gets value 1. The SSR3 bit value is automatically reset when client reads it. | |
| Event enable | Unchecked 1 | No Modbus events generated from this point. |
| Checked | Modbus event is generated when the value changes. Accurate event time stamp is inherited from IEC 61850 level. | |
| Rising edge only | Unchecked 1 | Modbus event is generated from both value transitions; from 0 to 1 and from 1 to 0. |
| Checked | Modbus event is generated only from 0 to 1 transitions. |