Excerpt: AISG RET cables come in 4-pin, 5-pin and 8-pin versions for remote antenna tilt control. This article explains their pin assignments, functional differences and compatibility limits. While the 8-pin AISG 2.0 standard cable offers full features and daisy-chain support, it is not plug-and-play compatible with simplified 4-pin or 5-pin cables. Learn key wiring tips and how to select the right AISG cable for your 4G and 5G telecom sites.
Remote Electrical Tilt (RET) antennas use AISG cables to deliver power and RS485 communication signals between RRUs, RET controllers and antenna RCU units. You will find AISG cables available in 4-pin, 5-pin and 8-pin variants. Many customers ask whether these cables can replace one another freely. This guide explains their functions, compatibility and essential engineering considerations.
AISG refers to the Antenna Interface Standards Group. The AISG protocol supports remote adjustment of antenna downtilt, RCU status reading and alarm reporting. A single AISG cable carries both DC power and RS485 differential data at the same time.
Below is a full comparison of specification, functions and compatibility for all three mainstream AISG cable types:
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Item
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8-Pin AISG (AISG 2.0 Standard)
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5-Pin Simplified AISG
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4-Pin Minimal AISG
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|---|---|---|---|
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Standard Level
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Official AISG 2.0 Full Standard
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Manufacturer Custom Simplified Version
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OEM Minimal Custom Version
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Core Signals
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+DC, GND, RS485 A/B + Reserved Pins
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+DC, GND, RS485 A/B + Aux/Shield
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Only +DC, GND, RS485 A/B
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Daisy Chain Support
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✅ Full Support (IN/OUT Port)
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❌ Mostly Not Supported
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❌ Not Supported
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Full RCU Functions
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✅ Tilt adjust, version read, alarm detection
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⚠️ Basic control only, partial alarm loss
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⚠️ Only simple tilt control
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Cross-Brand Compatibility
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High (Global Unified Standard)
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Low (Pinout varies by vendor)
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Very Low (Fully customized)
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Application Scenarios
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4G/5G new sites, multi-antenna cascading
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External RET controller, single antenna retrofit
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Internal short harness, OEM customized projects
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Plug-and-Play
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✅ Standard devices
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❌ Need pinout confirmation
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❌ Need custom wiring
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The 8-pin option is the official full AISG 2.0 standard cable. It dominates modern 4G and 5G site deployments.
Its pin layout includes DC positive, power ground, RS485 A, RS485 B plus several reserved empty pins.
Reserved pins stay unused under normal operation, yet they reserve space for future upgrades. This type remains the top recommendation for new site builds.
The 5-pin cable is a custom reduced version. It commonly appears on external RET drivers and older antenna systems.
It keeps the four core signals: +DC, GND, RS485 A and RS485 B. The fifth pin works as auxiliary wiring or shield ground.
The 4-pin model is the minimal AISG wiring solution. It only transmits +DC, GND, RS485 A and RS485 B.
Short answer: No plug-and-play compatibility, but it can work with custom harnesses.
The 8-pin AISG cable is the most universal standard. Its four core signals (+DC, GND, RS485 A, RS485 B) match the required signals for most 4-pin and 5-pin RCU units. You can build a transition cable by extracting these four core wires from the 8-pin connector to connect to 4-pin or 5-pin antennas.
Even so, several key limitations apply:
A: Not recommended. Pin definitions vary by manufacturer. Generic adapters may not work. Custom wiring based on the antenna datasheet is required.
A: No. 4-pin and most 5-pin RCUs lack OUT ports. Daisy chain is unavailable after conversion.
A: Incorrect RS485 A/B wiring only breaks communication. Wrong power and ground connection can burn the RCU unit. Double-check pinout before power on.
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