Selectronix, Inc.

Woodinville, WA

A Custom Product Development and Design Consulting Company


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Superstep Series 4000

The Superstep Series 4000 Load Controller is an all solid-state, microcontroller-based control unit for use in staged electric heating and cooling systems, such as hot water, steam,  duct heater, furnaces, chillers, compressors, and other HVAC systems. 


bulletOn-board configuration for:
bulletInput signal type:  0-5 VDC, 0-10 VDC, 2-10VDC, 4-20ma, Slidewire (135ohm), User-defined VDC or ma
bulletCompatible with Honeywell T775, T991, L91, and many more modulation controllers
bulletSLC4000 for 120 Vac/ 12Vac/14Vdc Power is now a UL Recognized Component for Canada as well as US.
bullet SLC4024  for 24 Vac/ 28Vdc Control Power is now a UL Recognized Component for both US and Canada and is in stock!

UL Certificate of Compliance for SLC4000 and SLC4024 

bulletVernier Output is adjustable with a potentiometer for 1x to 2x unit loads.  It is available as a separate option. 

Order SLC4000-4-01, SLC4000-4-03, SLC4000-8-01,SLC4000-8-03

         SLC4024-4-01, SLC4024-4-03, SLC4024-8-01,SLC402400-8-03

The Vernier output is a 0-10 VDC signal used to control an SCR power module or to provide the information on the fractional unit-load. The output is indicated by the intensity of a dedicated LED.  See the SLC4000 Vernier Product Change Notification

bullet2 std configurations: 4 relays and 8 relays
bulletQuantity of relays to utilize is field selectable
bulletThe units may be field- configured as either a master or an expansion board
bulletConnect a master and up to 3 expansion boards for a maximum system total of 32 steps. 
bulletRS-485 bus connects the units using standard Ethernet patch cables.
bulletMaster and expansion units may be separated by long distances, for a total length of 4000 feet!
bulletProgressive or Linear Sequencing 
bulletOperational or Dedicated Test Mode
bulletTest Up and Test Down pushbuttons assist in startup and troubleshooting
bulletOn Delay of up to 0-7 minutes plus 0-60 seconds.
bulletOff Delay selectable between either 2 or 5 seconds
bulletIntegral Load Limit input for managing peak demand charges
bulletBi-color Status LED indicates system mode.
bulletIndividual LED indicator for each step
bulletAlternate Function Relay - Any System Relay On
bulletAlternate Function Relay - All System Relays Off
bulletAlternate Function Relay - System Fault
bulletPilot Duty Relay Output Rated at 5A @ 250 VAC
bulletOptional Remote LED display
bulletUL Recognized XAPX2 Component (File E124742)
bulletMade in the U.S.A.
bulletSLC4000 Suffix Options:
bullet    -01   Vernier output, pot adjustable
bullet    -02   Load limiting input is 4-20ma.  Includes external 61.9 ohm resistor and quick connect adapters.  No Vernier output
bullet    -03   Vernier output with 4-20 load limit.  Includes external 61.9 ohm resistor and quick connect adapters.

Competitive Cross-Reference

Comparison Chart Viconics R851B and Selectronix SLC4000 



SLC4060   Process Gateway (PGW)

The Process Gateway provide analog and digital I/O for pinpoint control and monitoring


2 PID Loops 


2 RTD Channels


2 Analog Inputs


4 120VAC or 24 Vac/Vdc Digital Inputs


3 Relays


Voltage Driver, 0-10V dc


24V dc Auxiliary output to supply SLC4075-4 (4.3" screen)


UL Recognized Component


Made in USA

                                                                                 UL Certificate of Compliance for SLC4060 



SLC4075   Touch Screen Gateway (TSGW)

The Touch Screen Gateway provides the Human Machine Interface and the communication protocols for connecting the Building Management System


SLC4075-4   4.3" Color Touch Screen


SLC4075-7    7" Color Touch Screen with SD card slot for field upgrading


Control and Monitor PGW and SLC4000 parameters


Communication Protocol Support




Modbus TCP/IP, RS485, Serial


Alarm and Monitoring


Password and Multi-level Security Features




Download Manuals And Other Technical Information

Ordering Information


Selectronix Part Number

4 Step Control Unit  (Use for 1-4 Relays, 120VAC input power) SLC4000-4
8 Step Control Unit  (Use for 1-8 Relays, 120VAC input power) SLC4000-8
bulletPotentiometer adjustable Vernier Filtered DC Output for 1 to 2 Unit loads
Add suffix -01
bulletPre-programmed for Load Limit with 4-20 ma.  This option includes a 61.9 resistor for 4-20ma operation.
Add suffix -02
bulletPotentiometer adjustable Vernier Output for 1 to 2 Unit loads AND Load Limit with 4-20 ma. This option includes a 61.9 resistor for 4-20ma operation.
Add suffix -03
bulletPWM Vernier DC Output for 1 Unit load
Add suffix -11
bulletPWM Vernier DC Output for 2 Unit loads
Add suffix -21
4 Step Control Unit  (Use for 1-4 Relays, 24 V ac/28 V dc input pwr) SLC4024-4
8 Step Control Unit  (Use for 1-8 Relays,  24 V ac/28V dc input pwr) SLC4024-8
NEMA4X Enclosure, SLC4000-ready SLC4010
Cable, Cascading, 1 Ft (0.3m) SLC4020-1
Cable, Cascading, 2 Ft (0.6m) SLC4020-2
Cable, Cascading, 3 Ft (0.9m) SLC4020-3
Cable, Cascading, 6 Ft 1.8m) SLC4020-6
Cable, Cascading, 10 Ft (3m) SLC4020-10
Cable, Cascading, 20 Ft (6.1m) SLC4020-20
Resistor Adapter Assy, 61.9 ohm for 4-20 ma Load Limit input SLC4040-0061.9
Resistor Adapter Assy, specify resistance in ohms, xxxx SLC4040-xxxx
Process Gateway SLC4060
Touchscreen Gateway 4.3" Color Screen SLC4075-4
Touchscreen Gateway 7" Color Screen SLC4075-7
Building Management Interface Bundle includes TSGW, PGW, temperature sensor, and more. SLC4099-4 Bundle with 4" Screen              SLC4099-7 Bundle with 7" Screen
Remote Indicator Panel (8 LED) SLC2170-08

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Last modified: September 01, 2017