NXP Commands

Readers which support NXP commands report the same in the field isNXPCommandSupported of ReaderCapabilities as true. The following operations can be performed on NXP Tags:      

1. Set EAS – This feature can be used to set/reset the EAS (Electronic Article Surveillance) Bit. Tags can be monitored for EAS bit for the purpose of theft detection. For e.g. tags with EAS enabled moving out could be an indication of unbilled item or theft. The methods SetEASWait and SetEASEvent allow setting or resetting the EAS bits on one or more NXP tags. An NXP tag with EAS bit set will raise an NXP_EAS_ALARM_EVENT when running EAS SCAN (NXP_EAS_SCAN) on the reader.
2. ReadProtect and ResetReadProtect - The feature ReadProtect sets the Quiet bit on one or more NXP tags. The methods for the same are readProtectEvent and readProtectWait. As a result, these tags report a string of zeroes during Inventory and don't respond to access-operations, thereby preventing unsecure access to Tag information. To put them back into normal mode, one has to call resetReadProtectEvent.
3. Performing NXP Scan – To track NXP tags in which the EAS bit is set, an NXP_EAS_SCAN can be initiated on the reader by calling reader.Actions.TagAccess.NXP.performEASScan or reader.Actions.Inventory.Perform with its AntennaInfo parameter specifying NXP_EAS_SCAN as the OPERATION_QUALIFIER for at least one of the Antenna IDs in the AntennaList array.

   short[] antennaID = new short[reader.ReaderCapabilities.getNumAntennaSupported()];

   for (int nIndex = 0; nIndex < antennaID.length; nIndex++)

     antennaID[nIndex] = (short)(nIndex + 1);

     

   OPERATION_QUALIFIER[] antennaOpList = new OPERATION_QUALIFIER[reader.ReaderCapabilities.getNumAntennaSupported()];

   for (int nIndex = 0; nIndex < antennaOpList.length; nIndex++)

       antennaOpList[nIndex] = OPERATION_QUALIFIER.NXP_EAS_SCAN;

   AntennaInfo antennaInfo = new AntennaInfo(antennaID, antennaOpList);

    

4. Change Config -  NXP G2iL and G2iL+ tags support in addition operations for 'bank wise read protection', 'product status flag', 'back scatter strength reduction'. The G2iL+ tags also offer more advanced features like 'read range reduction', 'tag tamper alarm', 'digital switch', 'data transfer mode', 'external power supply', 'external digital input'. These additional features can be controlled (i.e. turned on/off) by modifying change Config word when the EPC memory bank of the tag is not locked. Config word is part of the tag's EPC memory and setting/resetting the bits of the Config word turns on/off the corresponding tag features.

     TagAccess tagAccess = new TagAccess();

           NXP.ChangeConfigParams ChangeConfigParams = tagAccess.NXP.new ChangeConfigParams();

           ChangeConfigParams.setAccessword(0x01);

           ChangeConfigParams.setNXPChangeConfigWord((short)0x0002);

   Given below is the list of the bits in Change Config word and the corresponding features.

                     Config Word

   Bit Offset	Content	Remark
   0	Tamper alarm flag ( G2iL+)	Indicator bit
   1	External supply Input(G2iL+)	Indicator bit
   4	Invert digital output	Temporary bit
   5	Transparent mode on/off	Temporary bit
   6	Transparent mode data/raw	Temporary bit
   9	Maximum back scatter strength	Unlocked memory
   10	Digital Output	Unlocked memory
   11	Read range reduction on/off	Unlocked memory
   13	Read protect EPC bank	Unlocked memory
   14	Read protect TID bank	Unlocked memory
   15	PSF Alarm flag	Unlocked memory

    

   Though, a 16 bit Change Config word on a tag with unlocked EPC can turn on/off certain advanced features supported by G2iL tags and  the tags reports back the modified Config word, setting the Change Config word to zero however does not change the current Config word but the tag still responds with current Config word.