Probably my best ever 180 degree panoramic of the port at Cartagena, Colombia. Here it is uncropped. January 2012.

Información, ideas y opiniones que no son confiables, rara vez actualizadas y de calidad dudosa.

Is this even remotely interesting?

the fascinating Epson TM-H6000III receipt printer I work in retail point-of-sale. Recently I troubleshot an issue with a receipt printer, and it required "refamiliarizing" myself with some concepts I haven't really kept on top of the past few years, and writing the short doc below:

A receipt printer must have some way to prevent the computer from sending data faster than the printing device can handle it. The Epson TM-H6000III employs 2 methods to prevent this from happening:
1. Either DTR/DSR (hardware) or XON/XOFF (software) flow control which involves sending special control characters from the computer to the printer and back to manage what gets printed and when. (Epson default is DTR/DSR. WinXP default is none.)
2. A print buffer into which the printer stores incoming data yet to be processed. (Epson default is 4kb)
In addition to the above, both the computer and the printer also manage their own baud rates, the speed at which the computer sends it's data and the speed at which the printer receives it. Baud rate can be loosely defined as the number of characters per second that a device can send to or receive from. (Epson default is 19200, WinXP default is 9600)
Because of the Epson TM-H6000III's large 4kb buffer, there is rarely any need to invoke flow control, but this may actually confuse configuration and troubleshooting efforts. This is because flow-control may be set incorrectly, and (should it be and instead of but here?) because of the printer's large buffer, flow control only rarely gets invoked - only rarely enough to cause trouble.
A good example of incorrect flow-control settings would be the default values for the Epson TM-H6000III and Windows XP. At their defaults and with a large print job, the buffer might fill up before Windows is finished sending the entire job. The Epson TM-H6000III would send a control code to Windows to "stop sending information for a second", but because Windows' flow control is set to "off", it would blindly continue to send data to the printer, overflowing the printer's buffer and causing printer errors.
And with respect to baud rate, on the surface, setting the printer's "receive" baud rate to 19200 characters per second vs. the computer's "send" baud rate of only 9600 characters per second would seem like a good idea to prevent the printer from getting overwhelmed, but keep in mind that serial printer communications are bi-directional, and setting baud rate in this way actually means you may overwhelm the PC! Generally, both the printer and the PC should be set to the same baud rate, and the rule of thumb is to use the slowest acceptable baud rate, because "more slow" equals "more stable".
Note: Since at 9600 characters per second you could literally deliver more than 6 feet of store receipt to the printer in only one second...9600 baud is a more than adequate baud rate setting for both the PC and the printer.
So, as you now can see, stable and reliable receipt printing can easily be achieved if certain configuration choices are made beforehand:
1. Turn off the Epson TM-H6000III printer.
2. Open up the dip switch panel underneath the Epson TM-H6000III:
a. Set DSW 1-7 from ON to OFF and DSW 1-8 from OFF to ON (Baud Rate to be 9600)
3. Hold down the "Feed" button and turn the printer back on enter Self-Test mode and to verify your settings.
4. To exit Self-Test mode. Turn the printer off, and then back on.
5. In Windows Device Manager Settings for COM1:
a. Verify baud rate is set to 9600
b. Set flow control to be "Hardware"
Happy printing!

The long and short of it is, I found this pretty interesting. Is it just me?

Is this even remotely interesting?
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