RS-232 Communications Options

The RS-232 Communications Options parameters control the delay between messages, and the format in which the scanner and host terminal exchange tag data messages. The firmware is programmed to accept one parameter at a time and then leave this Parameter Programming Mode. Therefore, each of the parameters must be programmed separately. The default values are shown in the Red boxes and also in the Parameter Defaults section earlier in this chapter.

RS-232 Delay

The RS-232 Delay option sets the minimum time the firmware waits before sending the next message. This permits lowering CTS by the host terminal to inhibit data from the scanner. This option was not available on previous scanners.

Messages can be delayed as follows.

•Hex 0 for no delay

•Hex 1 for a 10 ms delay

•Hex 2 for a 50 ms delay

Scanner/Scale Format

The Scanner or Scanner/Scale Format option permits forcing the data format to either scanner only format or Scanner/Scale format to accommodate the host terminal. In some circumstances a host terminal may not be able to handle the normal format sent to it. In that case, selecting one of these options permits the use of the other format.

The choices for this option are as follows.

•Hex 4 for Scanner only format

•Hex 5 for Scanner/Scale format

The normal (default) format for scanner only tag data messages is as follows.

•Scanner-Only Tag Data

•Message Format

Prefix Byte	Label Identifier	Tag Data	PPD	Terminator Byte	BCC Byte
Blue type indicates optional information

The normal (default) format for Scanner/Scale tag data messages is as follows.

•Scanner/Scale Tag Data

•Message Format

Prefix Byte	30	38	Label Identifier	Tag Data	PPD	Terminator Byte	BCC Byte
	Add	FC
Blue type indicates optional information

The difference between the scanner only and the Scanner/Scale format is that the Scanner/Scale format has an address and a function code following the optional Prefix Byte. For more detailed information on message formats refer to the NCR Scanner/Scale Interface Programmer's Guide (BD20-1074-A).

Good Weigh Tone

The NCR 7879 can be programmed to sound a tone following a successful item weigh function. Scan the Hex 8 tag to disable this function and the Hex 9 tag to enable it