Selecting a measuring range

Selection of measuring "Mode" and measuring "Range"

First decide whether the terminal should be parameterized via PDO (process data) or via CoE. PDO parameterization is recommended if the terminal is to be switched frequently during runtime. If the terminal is parameterized once during commissioning, the route via CoE is simpler.

Both ways use the same setting values.

The measuring "Mode" and measuring "Range" can be set

Selecting a measuring range 1:Fig.137: Process data "Mode", "Range"

The corresponding CoE settings then have no effect, they are locked against write access.

Note: AutoRange is also active if the PDO Control is mapped and therefore PDO Control.Range actually specifies a value. To use PDO Control.Range, please set PDO Control.DisableAutoRange = TRUE.

Selecting a measuring range 2:Fig.138: CoE 0x8000:0D, Mode; 0x8000:11, Range

To be able to select Mode/Range via the CoE, the process data 0x1600 (TwinCAT System Manager -> Process data tab, Sync Manager: 2, PDO assignment) must be deselected (then press the “Reload” button or “F4” to accept the setting).

Measuring mode

The measuring mode must be selected in each case (in CoE index 0x8000:0D)

Value

Measuring Mode

dec

hex

0

0x00

DC voltage

1

0x01

AC voltage

2

0x02

DC current

3

0x03

AC current

Selecting a measuring range 3:

Measuring Range

The Range value can be regarded as power of ten (10^x).

Selecting a measuring range 4:

RMS value in the AC measuring range

In AC mode only the RMS value of AC voltage is shown (no DC component).

Measuring range / Autorange

The Autorange function is enabled by default and can be disabled if required.

Selecting a measuring range 5:Fig.139: CoE 0x8000:09, Disable autorange

The Autorange function selects the best measuring range for the selected measuring Mode.

Note: The current measuring range "10" is a separate measuring mode in Autorange mode, i.e. the modes of 0.1/1 A and 10 A are not changed because different input contacts are used for this.

Selecting a measuring range 6:

Disabling Autorange (Index 0x8000:09, see note)

The Autorange function is disabled if the measuring range is not transferred (Tx PDO 0x1A00 selected) and "scaled" view is not active.

The limits for changing the measuring ranges are 10% above the full scale value (extended measuring range, larger range) and 10% of the full scale value (smaller range). If "Left aligned" view is selected, the limits are 100% and 5% of the full scale value.

The terminal has an extended measuring range if a larger measuring range is available (i.e. in the measuring ranges 300 mV/ 3 V / 30 V and 100 mA / 1 A). In Autorange mode the extended measuring range is used as a hysteresis range. In the extended measuring range overflow and underflow bits and the error bit are set at 115% of the normal measuring range.

If AutoRange is not to be used, the measuring range must be specified manually (via PDO or CoE 0x8000:11, see above):

Value

Measuring Range

dec

hex

255

0xFF

300 mV / 100 mA

0

0x00

3 V / 1 A

1

0x01

30 V / 10 A

2

0x02

300 V (voltage only)

Notice

Quasi-static signal required in AutoRange mode

The AutoRange function requires 8 measured values in the same measuring range for the measuring range decision. If the input signal changes too quickly (e.g. square wave signal 0/5V, 1 Hz, filter enabled), it cannot make a measuring range decision, the measured value freezes (TxPDOToggle - Index 0x6000:10) - unchangeable).
AutoRange must be disabled for such signals and a suitable measuring range must be selected manually (via PDO or CoE).