The Atlas Commander DCC Controller
by Mike Carson
The Atlas Commander establishes a new price/performance benchmark and ups the ante for entry level DCC systems. Although Atlas is a new name in DCC systems, the Commander is a re-branded Lenz "Compact" integrated DCC system. Lenz invented DCC and is a familiar German name associated with quality German engineering.
The Commander is priced below other DCC systems, being the lowest price system available. Although an entry level system, the Commander is a sophisticated integrated DCC system capable of powering three or perhaps four engines, and controlling turnouts via the DCC track bus. The Commander has considerable expansion potential, deriving to a large extent from its Lenz heritage and the presence of an XpressNet jack on the back of the unit. Although limited out of the box to supplying 2.5 A, the Commander design includes an output to drive an external power booster, such as the Lenz LV101. Additionally, the Commander features an XpressNet (a modified RS 485 bus with two signal lines and two power lines) port to connect to other control devices, such as handheld controllers and turnout control panels. It is possible to daisy-chain devices on the XpressNet.
The Commander is an integrated bus controller/ power station capable of supplying 2.5 Amps of DCC power, addressing 99 separate locomotives, and controlling 99 turnouts. Although the Commander is capable of addressing and controlling significant numbers of locomotives and switches, the practical limit is provided by the 2.5 Amp current capacity limit.
The Commander case is a molded plastic enclosure, reminiscent of a large calculator, measuring approximately 8 inches long, 4.5 inches wide, and 2 inches high. The most connections are made to an eight position euro-style terminal strip at the back of the unit. In addition to the terminal strip there is an XpressNet connector on the rear of the unit.
The Commander terminal strip will accept 18 AWG wire, but will not accommodate 16 AWG wire. As a general DCC practice, the largest possible physical wire size should be used to connect the Generator to the Commander and the Commander to the track to minimize the power drops in the wiring. As the American Wire Gauge (AWG) measurement system is an inverse measurement system, the larger numbers are smaller physical wire sizes. Using 18 AWG wire with the Commander is suggested.
The Commander controls and displays are located on the top surface of the unit. There is one rotary speed control located at about the five o’clock position with two direction momentary push buttons (forward & reverse) immediately to the left of the speed control. The emergency stop push button is located above and to right of the speed control. The function switches (F0, F1, and F2) are above the speed control in about the center of the unit.
The display, a three digit seven segment LED display with two associated increment/decrement push buttons, is located at the eleven o’clock position. The display usually displays either an L (for locomotive) followed by a two digit number or an S (for Switch) followed by a two digit number. The specific locomotive or switch to be addressed is selected using the increment/decrement switches, labeled with a + and – symbol respectively. The increment/decrement switches are dual mode switches where pushing and releasing a button will change the address one count while holding a button down will change the address continuously until the button is released. The direction of travel commanded is annunciated by either upper or lower half of the colon between left hand and middle LED digits. When the upper half is illuminated, the forward direction is selected. Similarly when the lower half is illuminated, the reverse directions is selected. When the various functions (F0, F1, and F2) are selected, the decimal points associated with left digit, middle digit, or right digit illuminated respectively. When the track power is off, either because the stop button was pushed or a current overload has occurred, the word OFF flashes in the display.
The Commander is powered from a separate 14-18VAC, 50va +/- 5va, source. Atlas provides a suitable transformer, identified as the Generator. The Generator is an encased transformer with an integral AC power cord and two spring loaded euro-style output power jacks. The one shortcoming noted with the Generator/ Commander combination was the absence of an on/off switch. In order to turn off the Generator it is necessary to unplug the power cord.
The Commander is capable of programming decoders, setting speed steps (14, 28, or 128 steps) and creating custom speed curves. One limitation of the Commander is the restriction to short decoder addresses (02-99), as 01 is reserved for non-DCC equipped locomotives and 99 is the largest two number. The addressing limitation prohibits the use of locomotive long addresses. The Commander has an eight address recall stack, permitting rapid access to control locomotives. Because of the Commander power limitations, the addresses of all active locomotives are likely to be in the stack, simplifying the operation of the system.
Although the Atlas literature is contradictory on the point, the Commander does permit "consisting" (where multiple engines respond to the commands sent to the lead engine), if the locomotive decoders support the feature.
The Commander Instruction Manual is a reader friendly document, written assuming the first time reader is a novice to DCC. The manual explains how to connect the system components, select and control locomotive and switches, program decoders, and change system settings. As appropriate for an entry level system, the manual isn’t a treatise of the technical details of DCC systems, but a step by step instruction on setting up and running the Commander. The manual available on the Atlas website (www.atlasrr.com) in the DCC section. The Lenz "Compact" manual is available on the Lenz website (www.lenz.com).
The internal circuit board was examined and judged to be first class. The circuit board is a double sided printed wiring board utilizing surface mount components primarily. The exceptions were the speed control potentiometer, a large filter capacitor on the low voltage AC input and a socket mounted micro-processor. In short the Commander internals reflect quality engineering and construction. Although Atlas provides a one year limited warranty, the Commander should offer years of trouble free operation as the result of its robust design and construction. One implication of a socket mounted micro-proccesor is the Commander could be upgraded, with little effort to provide additional features, by replacing the micro-processor. Although there are no announced plans to upgrade the Commander, Lenz has upgraded the software in some of its DCC components in the past.
The Commander was tested on a large layout with a dozen or so DCC controlled switches (turnouts) and performed well. Perhaps the most unsatisfactory aspect of the Commander test installation was the DCC control of the switches. The Commander switch control methodology, while workable, was inconvenient. The Commander requires each switch needed to be individually selected and aligned to the selected route. Lenz has developed an auxiliary XpressNet controller, the LW100, especially to simplify the control of DCC accessory decoders (switches). The LW100 has the capability of aligning multiple switch routes with a single button push and connects to the Commander through the XpressNet connector on the back of the unit.
Part of the installation tests included determining the maximum electrical load. The Atlas Commander consistently supplied the rated 2.5 Amp of track power. Assuming quality HO engines, unlighted rolling stock, and stall motor switch machines, the Commander should power two engines and ten to twelve switch machines without reaching the electrical limit.
The Atlas Commander certainly deserves serious consideration by the modelers beginning with DCC and for intermediate modelers installing a DCC system on a small home layout. Although there are aspects that are less than ideal (such as the clunky switch control methodology and the short locomotive address restriction), the Commander can be enhanced and upgraded. By adding additional Atlas and Lenz components, most of the limitations can be corrected.
In conclusion, Atlas has established a new price/performance benchmark for entry level DCC systems with the Commander. The street price for Commander/Generator combination is significantly less than the MRC Command Pro. And when combined with Atlas/Lenz expandability and enhancement potential, the Atlas Commander is the preferred DCC entry level system.