PAT Testing with Barcode Scanners
Or What to do when your bored on a Sunday Afternoon!
Over the past few years talking with Pat Testing engineers using barcoded appliance Id labels they often encounter problems when reading them with their PAT Tester.
First of all the Barcode scanners supplied to work with Pat test machines are often of the proximity type, such as this DataLogic 6065.
These scanners have a couple of issues, first of all they are proximity scanners and require you to drag the head of the scanner across the label at very close range. Secondly they connect to the PAT tester with a cable, this makes reaching under desks etc very cumbersome and slow.
Although I enjoy working on the programming for SimplyPats I thought I would get the soldering iron out and see if I could develop a better solution for reading barcode labels.
First stop was to acquire an excellent DataLogic Gryphon scanner.
This scanner is designed for Electronic Point Of Sale (EPOS) and as such allows you to scan at quite a distance from the label. You don’t have to physically drag the scanner head over the label, but simply point and shoot! As an added bonus it shines a long red light bar on the label and then a green spot light when the label has been scanned. In addition you get a satisfying sound! All very Star Trek!
Now to make the Scanner work with Bluetooth. For all those experts out there, yes I know you can already buy Bluetooth scanners, however they are kind of expensive and also many require a base station to charge the scanner and accept the data. Also PAT testers almost always have a Serial DB9 connection for the Barcode Scanner whereas a lot fo the EPOS scanner solutions come with USB or PS2 (Known as a Keyboard Wedge) solutions.
First of all a bit of displacement shopping with the help of Maplins and Rapid electronic component shops.
The case for the bits!
Now the electronic bits. A toggle switch to turn power to the scanner on and off. A double A battery holder to hold 2 AA Cells, A 5 Volt Led with built in current limiting resistor, to show when the scanner is on. Finally a wonderful circuit built by Bodhilabs in the USA which converts 3 Volts DC into 5 Volts DC. Most barcode scanners are powered by 5 Volts DC as are the Serial to Bluetooth dongles commonly available.
Also required is a pair of Serial to Bluetooth dongles to communicate between the scanner and the PAT tester.
Ok so now the construction. First a few holes for the switch, led, cable gland, and arial from the bluetooth to serial converter.
Next to prepare the RJ45 cable that connects the scanner to a Serial Port. This is known as a CAB-327 cable and at one end has a special (10 pin NOT the usual 8 pin!) RJ45 connector and at the other a female RSR232 socket.
The cable is cut back just to leave the RJ45 connector, a few millimetres of the grommet and the Yellow, Brown and Orange wires. These are Orange TX or Data containing the Data sent from the scanner. Brown – Ground or 0v DC, and Yellow – 5v DC.
In the first stage of the assembly with the AA battery holder. The 3 V to 5 v circuit and the toggle switch, already mounted in the case.
Now both inputs attached to the circuit including the on off switch.
Now the LED added using a grommet to secure it in the case. The battery holder now positioned in the case with the 3v DC to 5v DC circuit hidden underneath it.
Now the LED is complete in the circuit and some male pins extracted from a sacrificed Male RS232 plug have been soldered to the data line, Ground and 5 V DC.
Now that the case is flipped over you see how the RJ45 fits into the large hole we drilled. The Brown, Yellow and Orange cables from the connector connecting to the 5v DC circuit all hidden underneath the battery holder. Notice also the spare hole! This is for a bolt to secure the scanner to the box of bits!
At this stage the batteries and the Bluetooth to serial adapter has been added. This BTWIN Bluetooth to Serial adapter has been paired with another so that they will only talk to each other and not try and connect with someone’s mobile phone or pc!
The Bluetooth to Serial adapter is powered by PIN9 being the 5V DC, PIN5 Being ground and PIN2 Being TX or Transmit Data. The Bluetooth to Serial adaptor has also had to be programmed so that it is using the correct BAUD rate Stop Bits and Parity. In the case of our PAT tester this was 9600,7,2
Finally a long thread bolt is used to attach the barcode scanner to the box of bits. This uses the existing thread of a bolt hole at the base of the scanner.
Also a nut has been added to secure the aerial socket of the Bluetooth to serial converter. We could have added a Bluetooth aerial but they seem to get snapped off or broken after a period of use. Even without an aerial you get at least 10 metres usable range.
With the scanner on its side you see the battery compartment hatch removed. After lots of testing, two 2300 mA AA Cells give about a day and a half scanning in the field. So a battery charge and some spare AA cells are essential!
Finally the completed scanner! At this point all that is needed is to plug the second Serial to Bluetooth dongle into the PAT tester and scan away!
This is a project that I thought would be a bit of fun to try out.
Although we have a few of these scanners out in the field working, if you do decide to have a go yourself, we accept no responsibility if damage is caused to yourself, your PAT Tester or any of the components used.
The above post is intended to show that it is possible to obtain a high quality Bluetooth Barcode Scanner for use with PAT Testers. However given the currrent cost of bluetooth scanners, Im not sure that this do it yourself solution is cost effective. Also as the wired scanners are not designed for battery operation they tend to use up AA batteries frquently. I suspect the commercial bluetooth scanners are designed to use less low current.
Thanks to Paul at Electratest Cornwall for providing a steady soldering hand.