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Remtron Brand

Built to perform and survive in the tough environments of steel and manufacturing plants, the Remtron ® brand flagship Command Pro product line sets the standard for reliability and ruggedness. Yet, inside each transmitter you’ll find a sophisticated electronic system that provides a higher level of responsiveness, versatility and safety.

The Command Pro line is available in various models offering different levels of functionality to meet the specific needs of different size facilities and types of applications.

Contact Laird Technologies today for your complete application solutions. 


  • Up to 40 functions
  • On/Alarm and Off/Stop buttons
  • Up to 4 step-less single axis levers or 3 dual axis joysticks
  • Up to 8 toggle switches
  • Optional multiplex selector
  • Optional key switch
  • 300+  ft. line of sight range


The Remtron Command Pro® equipment operates in the range from 902 to 928 Megahertz(MHz). A wavelength at our frequency is 12.9 inches. The 400 MHz band used by most other manufacturers has a wavelength of 29 inches. Like light, 900 MHz radio signals will pass through glass and plastics, and will reflect off of walls, buildings, and metal structures. Unlike light, 900 MHz radio signals will penetrate all plastics, including those that you cannot see through, thin-gauge steel, dry wood, dry concrete, plasterboard, fog, and rain. Trees, earth, water, people, aluminum, copper, and some window tints will not pass our signals. Antennas convert radio signals into radio waves and convert radio waves back into radio signals. They can send and receive in all directions or in a single direction, depending on their design. An omnidirectional antenna is like a light bulb, and a directional antenna is like a flashlight. Metal objects reflect radio waves, just as a mirror next to a light bulb will reflect light. Metal objects near an antenna alter the intended pattern of an antenna by either shading or reflecting signals.
Our standard antennas “see” equally well in all directions. We have other antennas that will “see” further in one direction for special applications. Our transmitters and receivers are designed to have more than a 2.5-mile operating range in “free space” (an unobstructed view). Our systems are range-tested to 600 feet, and we guarantee 300-foot performance. The extra signal strength provides a large margin, which allows for reliable operation in the presence of objects that can reflect or absorb radio signals.

The 902 to 928 MHz spectrum accommodates many license-free users and is set aside by the FCC as an ISM Band (Industrial, Scientific, and Medical). We have the ability to change frequencies in this band and have 85 different channels that we can assign to our transmitter and receiver. The actual frequency is coded into the receiver and transmitter at the factory but may be changed to one of the other 84 channels in the field. Other devices in this band include wireless phones, computer data links, and inventory equipment. As a condition of using this band, we must accept and handle interference from other users. The 900 MHz band has worked well for most users, and not being burdened with licensing regulations is always desirable. The FCC has allowed 50,000 microvolts per meter field strength on this band, which is 250 times higher than other unlicensed frequencies below this band. This allows our systems to operate very reliably in the presence of other signals.

We use Packet Mode Frequency Modulation to carry commands in a packet form from our transmitter to our receiver. To reduce battery drain, our transmitter transmits for a hundredth of a second, which is long enough to send one packet to our receiver at a repetition rate of 16 or 4 times a second. The rate varies: 16 times a second for three times when sending a command and four times a second when there is no change in commands and the transmitter is still on. Any time a lever or switch is activated, we send all control settings three times at the 16-per-second rate and then return to the slower rate of 4 times per second. Our receiver uses the slower rate for maintaining transmitter timing and provides for a maintained link where one is used. The only exception to this is the “ESTOP” switch, which transmits at 16 times per second as long as it is depressed. In addition to lever and switch positions, each packet contains a unique address and CRC check sum (described in the next paragraph). Safety and preventing loss of control are very important issues at Remtron. We use a unique identification code for each user. There are provisions in our system for 65,535 individual codes. Each transmission includes a CRC check sum, which is a polynomial created by factoring all of the previous bits transmitted. Once our receiver receives a valid start command from our transmitter, our receiver tracks the time of the transmitter and ignores all other transmissions that do not fall within the expected time frame of our transmitter. Maintained link systems must receive at least one valid transmission each second in order to allow the remote controlled equipment to function. Our receiver provides a loss-of-signal control output that safely shuts down the equipment if a loss of signal occurs. Our receiver will not allow restart of equipment under its control after a loss of signal until a valid system start command is received from our transmitter. This prevents an untended start-up from occurring if the transmitter returns within range of our receiver and is still operating. Our transmitters also check the position of all controls upon start-up. Our transmitter will not issue a start command if any of the controls are pressed at the time the start command is invoked. Exceptions for lights, horn, bell, or other user functions that do not place machinery in motion can be mapped into our control logic upon request. The 900 MHz band has other users, but because we are only expecting a 300-foot range, we have experienced very little interference from other users. Spread-Spectrum and frequency-hopping devices are used in this band. They are allowed ten times the field strength that our transmitters are allowed. Spread spectrum transmitters are required to spread their power out over a large bandwidth (Spreading Code) and the maximum power they can radiate in our bandwidth is only a few percent of our allowed transmitter power. It would take several of these devices close to our receiving antenna to cause our equipment to go to the fail-safe mode. Frequency-hopping devices are required to use 50 or more channels, recognize other transmitters on frequency, and hop over them. A frequency-hopper may cause us to lose one command sequence from our transmitter, but because each command sequence is sent three times, our receiver will still receive each command sent. Radio waves diminish as the square of the distance, so a transmitter with ten times the power will be the same signal strength at 3.16 times the distance of our transmitter from our receiver. FM systems also have a capture effect, where the strongest signal will capture the receiver, which rejects the weaker signal. The operator is seldom more than 300 feet from the equipment he is operating. His transmitter is the strongest signal present unless other equipment on this band is allowed to operate within 1000 feet of the location of the receiver. In summary, Remtron has developed a very robust proprietary digital communication protocol that will survive the harshest RF environment, including other signals present on the 900 MHz band.


Remote Control Solutions for Industrial Applications


Technical Data & Specification

RF Characteristics

RF unit Microprocessor controlled PLL synthesizer with up to 85 different channels
Frequency Range 902-928 Megahertz (MHz)
Channel Spacing 300 Kilohertz(KHz)
RF Power FCC Part 15: 50,000 microvolts per meter field strength
RF Approval License-free in North America
Industry Canada Certification # 249 710 31889
Modulation Packet Mode, Digital Frequency, Modulation(FM) based on Manchester code
Response Time 60 Milliseconds
Update Rate 16 packets per second command, 4 packets per second idle
Range 300- ft. obstructed view, 1000-ft. line of sight (unobstructed)
Antenna Front Mounted

Specifications are subject to change without notice. Check with the factory for confirmation.  

Safety and Operational Characteristics

Maintained Link Receive at least one valid transmission each second to continue operations
Loss of Maintained Link Safety shutdown, positive restart required
Addressing 16-bit, 65,535 unique addresses with 85 channels providing over 5 million variations
Safety Decoding 16-bit Cyclic Redundancy Codes (CRC) check
Safety Stop Over-riding Stop command with safety relay
Start-Up Safety Start inhibited if controls pressed before start
Inadvertant Command Safety Programmable time-out requiring positive restart (Push-to-Operate(PTO) commanding mode available)
Status Indications LED indicators with status for power, active transmission and low-battery and failure (or control pressed on Start)
Battery Type 3, 6 or 9 standard AA
Battery Operating Time Up to 350 hours of continuous operation

Specifications are subject to change without notice. Check with the factory for confirmation.  

Environmental Characteristics

Temperature Range -20° to +160° F (-29° to +71° C)
Humidity Range 0-97% maximum non-condensing
Environmental Protection Humisealed electronics
UL Rating UL 508 (Class I, Division I, and Group D and Class II, Division I and Groups E, F, and G also available)

Specifications are subject to change without notice. Check with the factory for confirmation.  

Physical Characteristics

Style One-axis levers or two-axis joysticks
Main Components Surface mount technology, single board design
Housing Material Vacuum molded
Weight 4.0 lbs. (1.814 kg)
Dimensions 5” x 10” x 7”   (12.7 cm x 25.4 cm x 17.78 cm)

Specifications are subject to change without notice. Check with the factory for confirmation.  

Machine Control Units

  21R22 21R22Z 21R30 21R30Z 21R44 21R44Z 21R52 21R52Z 21R66 21R66Z
21T34A X   X   X   X   X  
21T34Z   X   X   X   X   X
21T36A X   X   X   X   X  
21T36Z   X   X   X   X   X
21T42A X   X   X   X   X  
21T42Z   X   X   X   X   X
21T46A X   X   X   X   X  
21T46Z   X   X   X   X   X
21T54 X   X   X   X   X  
21T74A X   X   X   X   X  
21T76A X   X   X   X   X  



  • NEMA 4 enclosure
  • 21 control relays/ 1 alarm/ 2 safety relay
  • 120 VAC power supply
  • Terminal strip connection
  • Standard Industrial Enclosure
  • Dim: 14" x 12" x 6"
  • 21R22 Specifications


  • NEMA 4 enclosure
  • 29 control relays/ 1 alarm/ 2 safety relay
  • 120 VAC power supply
  • Terminal strip connection
  • Standard Industrial Enclosure
  • Dim: 14" x 12" x 6"
  • 21R30 Specifications


  • NEMA 4 enclosure
  • 43 control relays/ 1 alarm/ 2 safety relay
  • 120 VAC power supply
  • Terminal strip connection
  • Standard Industrial Enclosure
  • Dim:Varies upon application
  • 21R44 Specifications


  • NEMA 4 enclosure
  • 51 control relays/ 1 alarm/ 2 safety relay
  • 120 VAC power supply
  • Terminal strip connection
  • Standard Industrial Enclosure
  • Dim:Varies upon application
  • 21R52 Specifications


  • NEMA 4 enclosure
  • 65 control relays/ 1 alarm/ 2 safety relay
  • 120 VAC power supply
  • Terminal strip connection
  • Standard Industrial Enclosure
  • Dim: Varies upon application