Primary Values; Register Size; Control Operations; Control Functions - ABB Remote I/O RIO600 Installation And Commissioning Manual

Section 7
Modbus TCP communication
7.1.18
7.1.19
7.1.20
7.1.21
176

Primary values

Measurands originating from sensor measurements can be obtained from RIO600 in
only one way. They can be viewed as primary values. The primary values are
represented internally as decimal numbers. The primary units are [A] for current and
[kV] for voltage.
For each of these values mapped to the Modbus address, a scale factor is associated for
each of the values mapped to the Modbus address. The measurands are sent over two
Modbus registers using 32 bits for each measurand value. The Modbus master must
use the scale factor associated with each of these data points (mentioned in the point
list) and divide the value received over Modbus with the scale factor of that
measurand. For example, a value of 23.33 with a scale factor of 1000 is sent as 23330
to the Modbus master.

Register size

In most cases, the channel values of counters RTD4 and AOM4 are located in single
16-bit registers. In some cases, the measurands for SIM8F/SIM4F module are located
in two consecutive registers forming a single 32-bit integer value. The 32-bit value is
always coded so that the high word part, that is, the higher 16 bits, is located first in this
register address. The low word part, that is, the lower 16 bits, is always in the next
register address. Register sizes and types are stated in the Modbus memory map list.

Control operations

RIO600 outputs can be controlled either through the 0X coil objects or 4X holding
register control structures. See the Modbus control objects' memory map for the
available control objects. The control objects in RIO600 are single point control
objects. Single point control objects can be either pulse outputs or persistent outputs.
The Modbus client should only write "1" to the pulse outputs. This write operation
activates the control operation and there is no need for the Modbus client to write "0"
to the object. However, writing "0" is not forbidden. The result is that nothing happens
to the control object. The Modbus client can write both "1" and "0" to the persistent
outputs. Therefore, the persistent outputs have two defined levels: "0" and "1".

Control functions

The output objects are controlled one at a time. RIO600 accepts only functions 05
(force single coil) when the 0X coils control structure is used for the control operation.
The same can also be handled using the 4X register writes, that is, by using the feature
called direct control. The IED's analog output can be written only through function
code 06 (write single register).
RIO600 accepts force single coil (function code 05) when the 0X coil control structure
is used and write single register (function code 06) when the 4X register control
1MRS757488 H
Installation and Commissioning Manual
RIO600