{"product_id":"unitary-relay-controller-honeywell-pub6438sr-spyder-bacnet","title":"Unitary Relay Controller | Honeywell PUB6438SR Spyder BACnet","description":"\u003ch2\u003eHoneywell PUB6438SR Spyder BACnet Programmable Controllers\u003c\/h2\u003e\n\u003cp\u003eThe \u003cstrong\u003eHoneywell PUB6438SR\u003c\/strong\u003e, also cataloged as the \u003cstrong\u003ePUB6438SR\u003c\/strong\u003e Programmable Unitary Controller, operates as a dedicated hardware component for unitary HVAC sequence execution within BACnet MS\/TP building automation networks. Communicating over an EIA-485 physical bus layer, the controller processes 6 universal inputs and 4 digital inputs to govern modulating analog outputs and 8 electromechanical relay outputs. The hardware integrates a dedicated Sylk bus interface to power and query two-wire wall modules while executing deterministic control logic configured via the NiagaraAX framework.\u003c\/p\u003e\n\u003ch3\u003eHardware Specifications\u003c\/h3\u003e\n\u003cfigure class=\"table\"\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003cstrong\u003eParameter\u003c\/strong\u003e\u003c\/th\u003e\n\u003cth\u003e\u003cstrong\u003eSpecification\u003c\/strong\u003e\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eModel\u003c\/td\u003e\n\u003ctd\u003ePUB6438SR\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePart Number\u003c\/td\u003e\n\u003ctd\u003ePUB6438SR\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBrand\u003c\/td\u003e\n\u003ctd\u003eHoneywell\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCategory\u003c\/td\u003e\n\u003ctd\u003eHVAC Controllers\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOrigin\u003c\/td\u003e\n\u003ctd\u003eUSA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003e0.45 kg\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDimensions\u003c\/td\u003e\n\u003ctd\u003e162 x 125 x 48 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOperating Temp\u003c\/td\u003e\n\u003ctd\u003e-40 to 65 deg C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePower Consumption\u003c\/td\u003e\n\u003ctd\u003e5.5 W\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eField Bus Protocol\u003c\/td\u003e\n\u003ctd\u003eBACnet MS\/TP over EIA-485\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInput Channel Count\u003c\/td\u003e\n\u003ctd\u003e6 Universal Inputs, 4 Digital Inputs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOutput Channel Count\u003c\/td\u003e\n\u003ctd\u003e3 Analog Outputs, 8 Relay Outputs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/figure\u003e\n\u003ch3\u003eDCS \u0026amp; Process Control Signal Interconnection\u003c\/h3\u003e\n\u003cp\u003eThe controller processes field telemetry and executes physical switching commands using standardized 4-20 mA HART and BACnet MS\/TP protocol interfaces. Integrated channel-to-channel isolation networks separate high-side 24 VDC\/VAC relay circuits from low-voltage microprocessor logic, preventing electrical transients from inducing control errors. Onboard cold junction compensation (CJC) algorithms maintain signal conversion accuracy across temperature sensor inputs during ambient panel temperature swings from -40 to 65 deg C.\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003eQ: How do the onboard relay outputs handle direct mechanical contact switching?\u003c\/p\u003e\n\u003cp\u003eA: The 8 electromechanical relay outputs provide isolated physical contact closures rated for direct switching of 24 VAC pilot relays, contactors, and equipment fan stages.\u003c\/p\u003e\n\u003cp\u003eQ: What precautions prevent communication disruption across the EIA-485 network segment?\u003c\/p\u003e\n\u003cp\u003eA: Technicians must wire all controllers in a continuous daisy-chain topology and engage 120 Ohm termination resistors at the physical end nodes of the BACnet MS\/TP bus.\u003c\/p\u003e\n\u003ch3\u003eField Installation Guidelines\u003c\/h3\u003e\n\u003cp\u003eMount the controller module onto a standard 35 mm DIN rail or secure it directly to a control enclosure backplate using mounting screws. Isolate main power sources before landing field wiring onto the removable screw terminal blocks. Route low-voltage universal input and Sylk bus cables through dedicated channels separate from high-voltage AC relay switching wiring by at least 300 mm to prevent electromagnetic coupling. Connect the EIA-485 cable shield drain wire directly to the main panel earth ground terminal at a single point only to eliminate circulating ground currents.\u003c\/p\u003e\n\u003ch3\u003eSEO Suite\u003c\/h3\u003e","brand":"HONEYWELL","offers":[{"title":"Default Title","offer_id":51284306624824,"sku":"PUB6438SR","price":250.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0893\/1616\/3896\/files\/PUB6438SR.jpg?v=1761557006","url":"https:\/\/www.automodulexpert.com\/products\/unitary-relay-controller-honeywell-pub6438sr-spyder-bacnet","provider":"AutoModuleXpert Ltd.","version":"1.0","type":"link"}