Setup of Analog Devices in Accord Builder
An Analog Device is an Analog Output signal generated by the PLC, representing an Analog command value,
Analog Inputs are items such as Level Transmitters, Pressure Transmitters, VSD Actual Speeds and signals from other PLC’s,
Following insertion in a unit, an analog input is configured with settings that will determine its operation and its description in documentation. During insertion, the input is given a name and short description. These may be changed at any time.
There are three tabs in the Analog Device properties configuration section. The name and units of the Device are given in the Current Item section. Cross reference, Save and Close buttons are also provided.
The following aspects of the device must be filled as required:
Address: This is the channel address of the device, in the PLC.
Output Type: This refers to the type of connection to the PLC, which will affect the scaling routine. The following types are configurable:
- Electrical Input e.g. 0-5 V, or 4-20 mA
- Bus based Input – Real – The signal is written to the Bus channel with applied Scaling Factor.
- Bus based Input – Word (Integer) – The signal is written to the Bus channel with applied Scaling Factor.
for Electrical Outputs:
Min Range: This is the lower value of the range in engineering units that the Electrical Output is to be scaled between.
Max Range: This is the upper value of the range in engineering units that the Electrical Output is to be scaled between.
For Bus Based Outputs:
Scaling Factor: The Factor applied to Bus Based Outputs in Engineering Units.
Engineering Units: The process units to be used in documentation and HMI controls.
Manual Only: Analog Devices are usually referenced in Programs or PID Loops. This option is used if the item is only required to be controlled manually. This allows the item to pass consistency check if it is not referenced by PID or program item.
IQ Information – this information is used in the automatic generation of the IQ document
Tolerance: This is the error allowed for a particular reading. It is in terms of the scaled engineering units value.
No. of Points: This is the number of readings that are to be tested during the IQ.
The IQ information fields are used to supply information for the IQ document.
In the IQ document a table is produced. Each row in the table is a test for the analog device. The number of rows is given by the No. of points above in the IQ set-up area. The Max and Min are always included and the other points are evenly spaced in the range e.g. an instrument of range 0 to 100 with 5 test points will be tested at 0, 25, 50, 75, and 100.
For each test point a tolerance is applied. This tolerance is the error that can be tolerated in order for the instrument to pass the test at that point.
The standard Siemens scale is 0 to 27648. The raw value being read by the PLC from the instrument item may be monitored in the register status area of Accord Builder.
The tolerance value input at Accord Builder is used to derive the equivalent value in terms of the raw value. This max raw value error is then shown in the table. The recorded value observed from the PLC must be within the raw value error in order for the instrument to pass the test.
E.g. An instrument of range 0 to 100 – the mid-range point of 50 would correspond to 27648 divided by 2 or 13824. If a tolerance of 1 is applied the possible error is limited to 276. The raw value being read from the instrument must be between and 13548 (13824-276) and 14100 (13824+276).
Card Setup Tab:
A PLC is composed of a CPU and I/O cards on racks, and in some cases communications processors, special function modules and bus based I/O.
Panel, Central Rack, Slot and Channel: These are all text input fields. Once a text is entered for a device or instrument, it then becomes available for other objects in the project. There is no validation on this information; the same combination of information could be entered for more than one device. This would be erroneous as each device must be unique, so care must be exercised in inputting the information. This can be filled in the IO Table in the Menu.
Type: The type of electrical signal associated with the analog input is also described in this tab. In this case a 4-20 mA signal is identified. The information stored in this area is used for documentation and does not comprise object data for PLC control.
Signal Setup Tab:
The following aspects of the device may be filled in if required:
Symbol: This may be an asset number or any unique identifier which describes the object within the entire company. This could contain references to the plant, the area within the plant, the unit and the digital input name itself.
Part Number: This is the supplier reference for the item.
Type Description: This is a general description of the type of item. If a type is entered, then it becomes available to all other objects of the same type.
Long Description: This describes the object in more detail, if required.
Supplied By: Name of the supplier.
Notes: General Notes on the object. This may contain reference to maintenance manuals, maintenance history or location and type of spare parts.