Description
Product Introduction
The Allen-Bradley 1788-MCHKR MediaChecker is a specialized, battery-powered handheld diagnostic instrument designed for rapid troubleshooting of industrial network cabling. It focuses on the physical layer (Layer 1) of field networks, allowing instrumentation technicians and automation engineers to verify cable integrity before commissioning or during emergency downtime incidents.
Unlike standard commercial Ethernet testers that fail on heavy industrial trunks, the 1788-MCHKR isolates complex physical faults specific to industrial environments—including DeviceNet thick/thin trunk lines, ControlNet coax, and standard industrial Category cable runs. It detects open circuits, shorted pairs, crossed conductors, split pairs, and precise distance-to-fault locations using built-in Time Domain Reflectometry (TDR).
Key Technical Specifications
| Parameter | Value |
| Supported Networks | DeviceNet (Thick & Thin media), ControlNet (Coax RG-6), EtherNet/IP (Cat 5/5e/6) |
| Primary Test Functions | Wire Mapping, Cable Length (TDR), Resistance/Impedance, Continuity, Shorts/Opens |
| Connectors / Ports | 5-pin Sealed Micro/Mini (DeviceNet), BNC (ControlNet), RJ45 (Ethernet) |
| Display Type | Backlit LCD Digital Display |
| Distance-to-Fault Range | Up to 2,000 feet (dependent on cable type and velocity of propagation) |
| Power Source | Standard 9V DC Alkaline Battery or External DC Power Adapter |
| Operating Temperature | 0 °C to +50 °C (32 °F to 122 °F) |
| Enclosure Rating | Ruggedized Industrial ABS Handheld Housing |
Application Scenarios & The “Trench” Experience
Picture this: It’s 1:30 AM, and an entire packaging line’s DeviceNet drop keeps dropping nodes randomly, dropping the main line every 10 minutes. The shift electrician replaced two scanner cards and three power supplies, but the network bus fault remains. The actual issue? A crushed trunk cable behind a cable tray, creating a marginal high-resistance short between CAN_H and Shield. Plugging in the 1788-MCHKR identifies the exact distance to the fault in under 30 seconds, pin-pointing the crushed cable section without tearing down 300 feet of conduit.
- Automotive Stamping & Body Shops – DeviceNet Trunk Testing – Verifies wire maps, terminating resistor placement (120Ω), and shield continuity across drag-chain cable runs.
- Process & Chemical Plants – ControlNet Coax Audit – Measures RG-6 coaxial cable runs for impedance discontinuities, damaged BNC connectors, and crushed trunk lines.
- Warehouse Conveyor Infrastructure – Ethernet Drop Diagnostics – Identifies broken RJ45 pins, split pairs, and cable length limits on long overhead runs to remote I/O drops.
- Greenfield Plant Commissioning – Cable Certification – Validates newly pulled field cabling for correct pinout wiring before powering up active network scanners.
Field Case Study: A food processing plant in Wisconsin suffered constant communication drops on its washdown conveyer line after a sanitation shift. The team suspected a blown PLC communication card. We dispatched an engineer with a 1788-MCHKR diagnostic set. Within 5 minutes of connecting to the field port, the MediaChecker revealed an open shield connection and a shorted line pair inside a flooded field junction box 85 feet down the line. Replacing the corroded connector restored the network, saving $35,000 in unnecessary card replacement costs.
1788-MCHKR
1788-MCHKR
Transparency SOP: Quality Assurance & Testing
We don’t just ship boxes; we test them on actual industrial cable runs. Every Allen-Bradley 1788-MCHKR unit undergoes our strict 5-stage bench verification process:
- Inbound Physical Inspection: Inspect outer casing integrity, LCD screen clarity, rotary switch contacts, and verify top connector ports (BNC, RJ45, 5-pin DeviceNet) for bent or recessed pins.
- Power-On & Screen Self-Test: Insert a fresh 9V battery, verify backlight operation, and run the internal diagnostic boot routine.
- Known-Good Cable Length (TDR) Calibration: Test the unit against precision-cut cable standards (10 ft, 50 ft, and 250 ft DeviceNet and Ethernet cables) to verify TDR length calculation accuracy within ±2%.
- Wire Map & Short/Open Fault Injection: Plug the tester into engineered fault harnesses (simulating split pairs, shorted CAN lines, open shield) to ensure 100% detection accuracy on screen.
- ESD Cleaning & Protective Packaging: Clean casing with ESD-safe solution, pack with a fresh battery and terminal accessories, and bundle inside protective anti-static bubble casing.
The Veteran’s Tech Trap Guide (Crucial Value-Add)
- ⚠️ Never Connect to an Active/Powered Network! The 1788-MCHKR is a physical layer continuity and TDR diagnostic tool designed for unpowered cable runs. Plugging this unit into a DeviceNet trunk with active 24V DC field bus power applied will blow the internal input protection diodes! Always isolate network power before testing.
- ❗ Calibrate the NVP (Nominal Velocity of Propagation) Setting: TDR cable length measurements depend on the cable’s NVP rating. If your length readings seem off by 10-15%, check the setup menu on the 1788-MCHKR to ensure the correct cable type (e.g., DeviceNet Thick vs. Thin vs. RG-6 Coax) is selected.
- ⚠️ Disconnect Terminating Resistors During Wire Mapping: When testing DeviceNet or ControlNet trunks for end-to-end resistance or continuity, disconnect the 120Ω terminating resistors at the ends of the line. Leaving them connected will skew resistance measurements and report false shorts across differential pairs.
- ❗ Check for BNC Connector Wear: The top BNC port on used 1788-MCHKR units can wear down from years of field use. If ControlNet readings fluctuate when wiggling the cable connector, clean the center pin receiver with electrical contact cleaner or use a BNC saver adapter.
Frequently Asked Questions (FAQ for Conversion)
Q: Is the Allen-Bradley 1788-MCHKR still in active production by Rockwell Automation?
A: No. The 1788-MCHKR is a discontinued/legacy diagnostic instrument. Sourcing high-grade bench-tested surplus or refurbished units is the primary way to replace lost or damaged field units without adopting expensive third-party diagnostic suites.
Q: Can the 1788-MCHKR analyze active network traffic or baud rates?
A: No. The 1788-MCHKR is strictly a physical-layer (Layer 1) cable and wire tester. It checks wire mapping, continuity, cable length, shorts, and resistance. To analyze active CIP network traffic, packet drops, or node addresses, you need an active network analyzer or software protocol tool (such as Frontline/NetScan).
Q: Does the 1788-MCHKR test industrial Ethernet cables?
A: Yes. The 1788-MCHKR includes an RJ45 port for testing standard 4-pair and 2-pair (D-coded) industrial Ethernet cable runs for wire mapping, length, and continuity faults.
Q: What accessories come with the unit?
A: Standard units usually ship as the handheld tester body. If you require specific test leads, terminators, or remote wire-map terminators, let our sales team know when requesting a quote so we can configure a complete field kit for you.
Q: Why buy New Surplus or Refurbished over third-party alternatives?
A: Third-party commercial cable testers often lack the dedicated connector pinouts (like 5-pin mini/micro DeviceNet taps) and specific impedance profiles required for legacy Allen-Bradley networks. Sourcing a dedicated 1788-MCHKR gives your shift technicians the exact tool built for your plant’s installed hardware base.
Q: What warranty is included with this diagnostic tool?
A: All our 1788-MCHKR units (New Surplus or Refurbished Tested) come backed by our full 12-month functional replacement warranty. If the unit experiences hardware faults during normal field use within 365 days, we swap it out.
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