Revision D 12/09

Chapter 4: Programming Commands  95

Unsolicited status mode

Select or cancel unsolicited status mode (USM)

ASCII:

GS a n

Hexadecimal:

1D 61 n

Decimal:

29 97 n

Value of n:

0 turns mode off; any non-zero value turns mode on

Default:

0 (USM disabled)

Enables or disables automatic return of 4 status bytes whenever one or more of the listed changes occurs. This command is a batch mode command; that is, it is processed after all prior data in the input buffer has been processed. There may be a time lag between the printer receiving this command and enabling unsolicited status mode (USM), depending on the pending input buffer contents.

If an immediate return of printer status is desired, then any of the other status commands should be issued following this command. Once this mode is activated, the printer automatically transmits 4 status bytes whenever any of the conditions change. If an RS-232C connection with hardware flow control is used, all four status bytes will be transmitted without checking DSR.

This command is a POS version of general printer unsolicited status functions; it uses the same command code as older versions of the POS command. “automatic status back (ASB)” but has the following differences:

The parameter n is an on/off switch; it does not select trigger subset

There is no immediate return when this mode is turned on

All 4 status bytes are always returned

A change in any of the following conditions will trigger the USM response:

Cash Drawer

Receipt Cover

Knife Error

Out-of-Range Printhead Temperature

Out-of-Range Voltage

Paper Exhaust Status

Slip Paper

Related information

When Unsolicited Status Mode is enabled using this command, the status transmitted by other commands and the USM status are differentiated according to the information found in Recognizing Data from the printer, which follows the USM return description.

The status bytes to be transmitted are described in the following four tables.

Byte 1 = printer information

Byte 2 = error information

Byte 3 = paper sensor information

Byte 4 = paper sensor information

A799-PG00001D

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Cognitive Solutions A799 manual Select or cancel unsolicited status mode USM, GS a n, Default USM disabled