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Field Inspection Manual — Non-Automatic Weighing Devices

Part 3, Section 10: STP-10: Sleep Mode


Sections 30 and 31 of the Specifications Relating to Non-automatic Weighing Devices (1998).


The sleep mode/zero feature of the device must be designed to ensure accurate measurement and prevent inadvertent errors. This evaluation is performed when the device is initially inspected to ensure that it has been configured properly.


"sleep mode" means a function of a device that blanks partially or totally the indications after a defined period of non use, in order to save the screen or to display information other than weights.


A device may go in a sleep mode or may display non metrological information such as advertisements, greetings, time and date, etc. provided that the following conditions are met:

The scale totally or partially blanks its indications or displays non metrological information only when the device is at "Gross" load zero (no load) and has reached a zero-balance condition.

If the device blanks its indications partially only or displays non metrological information, the displayed information cannot be construed as weight indications.

Printing function must be inhibited when the device is in sleep mode.

The scale must be provided with an automatic means to inhibit the weighing operation or return the device to a continuous digital indication when the scale is in an out-of-balance condition. Perform the test below.

Acceptable Alternatives

  1. The device may go into sleep mode with a load on the platter provided that it is designed to prevent any further weighing operations before the operator removes the load from the platter, cancels the tare and resets the device to zero. In this case the device must bear, adjacent to the weight display, the following marking: "The device is at zero when in sleep mode" or equivalent statement.

Means of Automatically Restoring Weight Indication


To ensure that the device is designed to detect an out-of-balance condition and return to weight indication. Also to ensure that the printing function is inhibited when in sleep mode. The following test is performed when the device is initially inspected only.


Ensure that the "sleep mode" function is activated;

Zero the device and wait until it goes to the "sleep mode" or displays non metrological messages;

In one firm motion (so as to prevent the AZTM from capturing part of the test load) apply a load equal to 1e. The non-zero/non-metrological registration must have been replaced by a mass registration equal to 1e;

Wait 5 minutes (or the normal delay for the device to return to the sleep mode) to see if the device will go into a "sleep" mode with a load on the platter;

Zero the device with the load on the platter and wait until a non-zero/non metrological indication appears;

Attempt to print;

In one firm motion, remove the test load equal to 1e. The non-zero/non metrological message must have been replaced by a mass indication equal to (minus) 1e, or by an under-weight indication.

Interpretation of Results

The device complies with the requirements if:

  • it does not go into a "sleep" mode when there is a load on the platter;
  • it returns to a weight indication when an off-zero condition exists;
  • the printing function is inhibited.

The device meets the requirements also if, in the case it goes to "sleep" mode with a load on the platter, it prevents any further weighing before the load is removed, tare is cancelled and the device is re-zeroed.


Rev 1. (June 2007)

  • Clarify requirement for marking the device when in sleep mode. This change corrects a contradiction between the Approval Evaluation Manual and this manual.
  • correct references to Specifications Relating to Non-automatic Weighing Devices (1998).
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