Pricom DCC Pocket Tester Review

by Larry Maier

• Buy DCC Pocket Tester
• DCC Pocket Tester Introduction

Pricom Design has released a DCC pocket tester. It measures 5 .75 x 3.63 x 1.25, so it will just fit into your pocket. It is designed to read the quality of the DCC data on your layout. Through the use of 17 different menus, the measured data are presented in various formats that allow you to completely examine how your DCC system is performing on your layout.

The Pricom website states that the unit is designed for people “building a DCC Command Station, Power Booster, or other DCC Powered Device”, so the DCC Pocket Tester is not designed as tool for use by all model railroaders. Small layouts will not benefit from the use of the DCC Pocket Tester unless you simply like to add gadgets to your layout. Large club layouts, however, might want to consider adding a DCC Pocket Tester to their arsenal of DCC equipment. Large layouts can start to show problems in DCC due to the length of the track runs. As the length of the track becomes longer, the layout can start to act as a transmission line. This means that the layout is large enough that the DCC pulses take a significant amount of time (in electrical time at least) to move around the layout. Earlier pulses can reflect from various points in the layout. Due to the time it takes them to move from one point to the other, they can actually interfere with later DCC pulses. In essence, this effect can cause DCC errors and strange, random behavior. Also, on large layouts, the amount of DCC traffic on the rails can cause response delays due to packet congestion. The DCC Pocket Tester is the tool of choice to help analyze these types of problems.

The DCC Pocket Tester has a 2.6 x 1.5 LCD dot matrix display. This allows the internal processor to show the measured data in a multi-line user friendly format. The unit has four “arrow” buttons for navigating through the various menus. A simple power connector ties the unit to the track. This input provides the DCC data and the power to operate the unit; no batteries or other power source are required. In addition to the power input, there is an RS-232 port for downloading software upgrades, and a PNET port for attachment to the Pricom RS-485 network. A SEL button is not mentioned in the directions, but appears to reset the measurements in each menu.

The unit I received had Version 1.0 software. The website indicated that the latest configuration is Version 1.3. I downloaded the PC Update software, the new configuration file, and a .NET file from the Pricom website. Per the user manual, I first installed the .NET software. This is actually software from Microsoft that relates to the installation environment. I then installed the Pricom Universal Uploader software. I followed the user manual directions and connected the DCC Pocket Tester to my computer's COM 1 RS232 port using the included cable and then started the upgrade software. I followed the user manual directions for updating the unit, and found that everything worked smoothly as stated in the instructions. Although the .NET file is over 23 MB and took some time to download, I had no problem at all upgrading the unit to Version 1.3. Pricom is to be commended for their smooth, simple approach to upgrading software.

After upgrading, I connected the DCC Pocket Tester to my layout. The initial Quick Summary menu showed the DCC system working correctly. The next menu, Bit Summary, showed normal bit operation. This menu also contains an indication of the DCC voltage. With a DCC voltage of 13.9 volts, the Pocket Tester read 13.7 to 14.0. This is somewhat more error than their stated value of 1%. The directions do say that this reading is not RMS, and therefore is approximate. I found that the fast update rate for the voltage made it difficult to read the tenths of a volt digit since it was continually changing.

Several menus give statistics on the length of one and zero bits and the number of bits failing to meet NMRA standards. These menus can help large layouts if there is bit interference problem. A packet summary menu gives the total packet count and the number of bad packets. This menu also gives the packet rate. On large layouts, control response can be limited by the packet rate. This is essentially how many commands can be sent in a second. With a large number of operating engines, the packet rate can limit the response time of an engine or accessory to a cab command.

Rather than detailing all of the menus here, I recommend that you go to the Pricom website (see above) for a detailed description of all of the DCC Pocket Tester functions. One problem I did find: the Pocket Tester does not have a separate display function for accessory addresses. Engine addresses and accessory addresses use different formats. The DCC Pocket Tester interpreted accessory addresses as engine addresses. The result is that some of the menus were contaminated with incorrect addresses that resulted from issuing macro commands to accessories. For example, the Pocket Tester reported the use of address 9465. This address is actually an accessory address interpreted as if it were an engine address. Hopefully, a future update will correct this problem and provide a separate menu item for accessory addresses.

Conclusion:

The DCC Pocket Tester is a well designed unit intended mainly to help verify command station and booster performance. For large layouts with high traffic volumes, the DCC Pocket Tester is useful to help determine where and when DCC errors are occurring. It can help isolated bit distortion and packet congestion problems that manifest themselves as unstable performance on large layouts. The DCC Pocket Tester is easy to upgrade, with Pricom indicating on their website the intention to provide future performance improvements as they are warranted.