Siemens 6ES7972-0BB12-0XA0 Bus Connector

RS485 PROFIBUS 9-pin Sub-D bus plug, 90° vertical outlet, with PG programming port, built-in disconnectable terminating resistor. Suitable for DP/MPI stations such as S7-300/400 and ET200M, inverters.

✅ Key Specifications

Communication rate: up to 12 Mbit/s

Cable outlet: 90° (vertical downward)

Configuration: with PG programming socket (programming cable can be plugged in online without disconnecting the bus)

Terminating resistor: built-in with toggle switch (ON/OFF, isolated)

Dimensions: 15.8 × 64 × 35.6 mm (W × H × D)

Bus standard: PROFIBUS DP / MPI (MPI network compatible)

Product status: PM300 active product, made in Germany, RoHS compliant

Features: pure hardware connector, no configuration required in TIA Portal / STEP7, plug-and-play

📌 Model Comparison for Selection

Suffix 12 = updated optimized version; older 11 series is gradually phased out

🛠️ Typical Application

1. MPI/DP interface of S7-300 CPU, IM153 interface module, ET200M slave stations
2. Inverters (MM440, G120 old DP board), DP instruments, remote I/O
3. Field commissioning: reserved PG port for PLC online monitoring, program upload and download without interrupting the bus network
4. Start and end nodes of the bus: switch to ON to enable terminating resistor; switch to OFF for intermediate stations

⚠️ Installation & Troubleshooting Notes

1. Wiring: A/B lines must be connected correspondingly, A to A, B to B. Communication fails directly if reversed. Siemens DP bus cable 6XV1830-0EH10 is recommended.
2. Terminating resistor rule: Only the first and last connectors on the entire DP bus shall activate terminating resistors; all intermediate stations must turn them off, otherwise packet loss and intermittent communication failure occur.
3. Clarification: It is only a physical connector, not a protocol converter. MPI cannot be directly converted to Modbus RTU.
4. Domestic alternatives: Compatible DP plugs (90° with PG) are available on the market. For 12 Mbit/s high-speed and heavy interference environments, original parts are preferred.

🌡️ Special Wide-temperature Version

SIPLUS anti-corrosion wide-temperature model: 6AG1972-0BB12-2XA0, -25~+70℃ with anti-corrosion coating, suitable for outdoor and corrosive environments.

Application Scenarios of 6ES7972-0BB12-0XA0 (90° Outlet DP Bus Connector with PG Programming Port)

Core advantage: Built-in PG debug port, programming adapter can be connected for online monitoring and downloading without removing the bus cable. Preferred for stations requiring frequent commissioning. Supports PROFIBUS DP / MPI up to 12 Mbps, 90° vertical outlet saves cabinet space for compact wiring.

1. Compatible Hardware Stations
2. S7-300 PLC (CPU315-2DP, 313-2DP etc., onboard DP/MPI port) – most widely used
3. S7-400 PLC, CP443-5 DP communication module
4. S7-200 (with DP expansion EM277)
5. ET200 series remote I/O: ET200M, ET200S, ET200B, ET200L (IM153-1/2/4 interface module)
6. Siemens DP inverters: MM440, MM420, legacy G120 DP option board, 6SE70 DC drives
7. Third-party PROFIBUS DP slaves: DP instruments, weighing modules, valve islands, encoders, temperature controllers, DP servo drives of other brands
8. Network Function Scenarios
9. DP bus master station (highly recommended for this model)

Located at the PLC master station, used for frequent commissioning, upload/download and online diagnosis. USB-MPI/DP adapter can be plugged into the PG port without breaking the bus, this is its mainstream application.

2. Start and end terminating nodes of DP bus

Terminating resistor toggled ON for connectors at both ends of the bus. If the master station sits at the end, the PG-equipped version is preferred.

3. MPI network communication

MPI communication between S7-300 and legacy HMI such as MP277 / TP170. This connector can be fitted on CPU or HMI side to reserve a debug port.

4. Compact wiring inside control cabinet

90° downward cable routing along cabinet base plate. Compared with 35° angled outlet, it fits densely arranged backplanes with limited cabinet space.

For intermediate stations with rare maintenance, select 6ES7972-0BA12-0XA0 without PG port to reduce cost.

III. Industry Applications

Machine tools: CNC lathes, machining centers, gantry machines (legacy 840D/810D PROFIBUS networks)

Packaging, textile and printing production lines

Water treatment, HVAC, air handling units, pump stations

Rubber & plastic extruders, injection molding machines

Cranes, conveying systems, automated warehouses

Power plant, metallurgy, petrochemical retrofitting & maintenance of legacy DP systems

1. Not Suitable Scenarios (Pitfall Reminder)
2. Not a protocol converter, DP/MPI cannot be directly converted to Modbus RTU
3. Not applicable for PROFINET (PN Ethernet)
4. Outdoor, corrosive and ultra-wide temperature (below -25℃) environments: use SIPLUS version 6AG1972-0BB12-2XA0
5. FastConnect stripping cable: this model does not support FC quick terminals; dedicated FC models are required

PROFIBUS DP Wiring Specification + Terminating Resistor Setting + Communication Troubleshooting Checklist

For 6ES7972-0BB12-0XA0 / 6ES7972-0BA12-0XA0 standard Sub-D DP connectors

Recommended cable: 6XV1830-0EH10 standard purple DP cable (shielded twisted pair with copper conductor)

1. Wiring Specification
2. Bus Topology Rule (DP only permits bus topology; star and tree topology forbidden)

✅ Valid: All stations connected in series on one main cable with two terminators at both ends

❌ Prohibited: Short branches, T-taps, star junction boxes (causes unstable communication)

If branches are mandatory, DP repeater (6ES7972-0AA01-0XA0) must be used

2. Baud Rate & Max Cable Length (single segment without repeater)

Repeater: Each repeater extends one segment and isolates signals; maximum 9 repeaters cascaded

3. Shielding & Earthing (root cause of most faults)
4. The outer metal shield of DP cable shall be crimped to the metal shell of the connector. Do not strip a separate wire from shield for PE connection.
5. Metal shell of all DP connectors connected to cabinet PE protective earth (equipotential bonding)
6. Power cables (inverter, motor power lines) and DP signal cables shall be routed separately, minimum spacing ≥20 cm. Cross at 90° if unavoidable.
7. Line reactors and filters shall be installed for variable frequency motors and high-power contactor circuits to suppress interference.
8. Avoid multi-point earthing of shield and cross-cabinet wiring with large potential difference, which creates ground loop and intermittent communication dropouts.
9. Pin Definition (9-pin Sub-D, DP standard)

Pin 3: B line (green)

Pin 8: A line (red)

✅ Mnemonic: Red=A, Green=B. A to A, B to B, consistent across the whole bus. A/B crossover causes communication failure.

A and B are differential signals inside the connector. Reversed wiring leads to no slave station found without short-circuit alarm.

5. Outlet & Installation

90° models (0BB12/0BA12): suitable for horizontally arranged backplanes inside cabinet, cable routed downward

35° angled outlet (0BB42/0BA42): suitable for cables entering from cabinet side

Avoid sharp bending of DP cable; bending radius ≥ 8 × cable diameter

Do not bundle DP cables together with servo power cables in the same trunking

1. Terminating Resistor Setting (Critical)

Side toggle switch on connector: ON = terminating resistor activated; OFF = deactivated

✅ Standard rule:

Only the very first and last stations on one DP bus shall toggle ON; all intermediate stations must stay OFF!

Master station at bus end: master connector ON, last slave connector ON, others OFF

Master station located in the middle of bus: master connector OFF, connectors at two remote ends ON

Common mistakes:

① No terminator activated at both ends → signal reflection, packet loss, intermittent failure, worse at high speed

② Multiple nodes with terminator ON → excessive bus load, unstable communication and slave failure alarms

③ Only one end terminator ON → signal reflection, sporadic faults

Note: The PG port on 6ES7972-0BB12-0XA0 does not carry built-in terminator. The PG adapter itself has no terminating resistor, it is only for commissioning.

III. DP Communication Troubleshooting Checklist (follow sequence for high efficiency)

Step 1: Visual Hardware Inspection (priority)

1. Check A/B wiring for reverse connection, loose contact, stray copper wire short circuit
2. Verify terminating resistor switches, confirm only two ends are ON
3. Check DP cable for damage, compression, heat exposure from power equipment
4. Confirm shield is reliably crimped and connector shell is well earthed
5. Check Sub-D connector is fully locked and not loose

Step 2: PLC Diagnosis (STEP7 / TIA Portal)

1. Online check CPU diagnostic buffer:

Fault: Station failure: usually cable issue, terminator setting, interference or slave power loss

Fault: Frame error, checksum error, synchronization error: mostly loose A/B contact, interference or baud rate mismatch

2. Hardware configuration: baud rate of master and all slaves must be identical, cannot mix 1.5M and 500K
3. No duplicate DP addresses. DP address range: 0~126. Master is usually address 2; duplicate addresses are forbidden.

Step 3: Segmentation Isolation Method (for hard-to-locate intermittent faults)

1. Split the bus into two segments and test separately to locate faulty section
2. Remove slaves one by one starting from the last station to find the faulty node
3. Suspected interference: replace with short DP cable temporarily and keep away from inverters and contactors
4. Suspected connector failure: replace DP plug directly (many faults come from aged spring contacts inside)

Step 4: Frequent Pit Summary

1. Ordinary 2-core shielded cable substituted for Siemens dedicated DP cable → impedance mismatch, unstable communication at high speed
2. Large ground potential difference, ground loop formed by shield earthing → slow intermittent dropout
3. Excessive bus length with baud rate set too high, exceeding length limit
4. Unstable 24V supply and large voltage drop for old EM277, IM153 modules
5. Ungrounded inverters and servos inject high-frequency interference into DP bus
6. Pulling PG adapter during commissioning loosens bus connector and causes poor contact

Step 5: Auxiliary Tools

DP bus tester: measure terminal impedance. When both ends are enabled, bus impedance is approximately 110 Ω. Readings other than 110 Ω at intermediate nodes are normal.

Online diagnosis table: observe cyclic loss and recovery of slaves. Periodic dropout is mostly interference or terminator problem.

1. Quick Commissioning Tips (for 0BB12 with PG port)
2. USB-DP adapter plugged into PG port during commissioning, no removal of original DP bus required, no impact on the whole network
3. Prefer 0BB12 if master station is at the end for convenient maintenance later
4. Select 0BA12 (without PG) for intermediate stations with minimal maintenance to save cost
5. Fault Quick Reference Table

1. 6ES7972 Full Series PROFIBUS Bus Connectors (DP/MPI Plugs)

Model Coding Rule

Prefix: 6ES7972 (standard DP connector); 6AG1972 (SIPLUS wide-temperature anti-corrosion version)

5th character: B = with PG programming port; A = without PG programming port

6th~7th digits: outlet angle & wiring type

12: 90° vertical outlet, screw terminal (standard type)

42: 35° angled outlet, screw terminal

52: 90° vertical outlet, FastConnect quick stripping type

60/61: 35° angled outlet, FastConnect quick plug

Suffix: 0XA0 (standard industrial grade)

1. Standard Industrial Versions (6ES7972, IP20, 0~+60℃)

1) 90° Vertical Outlet (downward routing in cabinet, flagship model)

Screw Wiring (not compatible with FC cable)

1. 6ES7972-0BB12-0XA0｜90°, with PG port (this model, preferred for master station)
2. 6ES7972-0BA12-0XA0｜90°, without PG port (cost-effective for intermediate slaves)

FastConnect Quick Plug (no stripping required for FC purple cable)

3. 6ES7972-0BB52-0XA0｜90°, with PG port, FC quick plug
4. 6ES7972-0BA52-0XA0｜90°, without PG port, FC quick plug

2) 35° Angled Outlet (cable entering from cabinet side)

Screw Wiring

5. 6ES7972-0BB42-0XA0｜35°, with PG port
6. 6ES7972-0BA42-0XA0｜35°, without PG port

FastConnect Quick Plug

7. 6ES7972-0BB60-0XA0｜35°, with PG port, FC quick plug
8. 6ES7972-0BA60-0XA0｜35°, without PG port, FC quick plug

3) 180° Straight Outlet (axial outlet, for OLM fiber module)

9. 6ES7972-0BB00-0XA0｜straight outlet, with PG
10. 6ES7972-0BA00-0XA0｜straight outlet, without PG

4) Matching Active Terminating Resistor (for bus end)

11. 6ES7972-0DA00-0AA0｜active terminator, improves signal for high-speed long-distance communication

III. SIPLUS Wide-temperature Anti-corrosion Series (6AG1972, harsh & outdoor environments)

Temperature range: -40℃ ~ +70℃, anti-corrosion coating, for HVAC, metallurgy and outdoor equipment

1. 6AG1972-0BB70-7XA0 (90° with PG, equivalent to 0BB12)
2. 6AG1972-0BA70-7XA0 (90° without PG, equivalent to 0BA12)
3. Selection Reference Table

1. Related Accessories
2. PROFIBUS standard cable: 6XV1830-0EH10 (purple DP cable)
3. DP repeater: 6ES7972-0AA01-0XA0 (extend segment, isolate interference)
4. OLM fiber link module: convert electrical DP to optical fiber for long-distance and heavy interference applications

Master station & frequent commissioning → BB (with PG); intermediate stations with rare maintenance → BA (without PG)

Ordinary wiring & standard DP cable → 12/42 (screw type); FC fast cable used → 52/60 (FC quick plug)

Backplane downward routing in cabinet → 90° (12/52); side cable entry → 35° (42/60)