Siemens 39RTMCAN Replacement for SIMATIC ET 200

Product Overview

Siemens 39RTMCAN Replacement for SIMATIC ET 200: Smooth Migration & Backward-Compatible Upgrade

The Siemens 39RTMCAN is an RTD (Resistance Temperature Detector) temperature input module designed for the SIMATIC ET 200 distributed I/O platform communicating over the CAN Bus fieldbus protocol. As legacy SIMATIC ET 200 CAN-based systems approach end-of-life or face spare-parts shortages, plant engineers and procurement teams increasingly require a reliable, drop-in replacement or a structured migration path that minimizes engineering rework, wiring changes, and production downtime.

TOPNLMS maintains verified stock of the 39RTMCAN module and offers full pre-shipment functional testing, ensuring every unit shipped has been validated against Siemens factory specifications before it leaves our warehouse in Xiamen. Whether you are replacing a single failed module in a running line or executing a planned retrofit of an entire ET 200 CAN station, our team can support your project from sourcing through commissioning guidance.

Compatibility Comparison Table

Seamless Upgrade Solutions

A successful migration of an ET 200 CAN temperature measurement station rarely involves only the 39RTMCAN module in isolation. In practice, field engineers replacing or upgrading this module will also evaluate the surrounding system components to ensure the entire station operates reliably after the swap.

The ET 200 CAN station head / bus coupler (the master node that bridges the CAN fieldbus to the individual I/O modules) is the first component to verify. If the station head firmware is outdated, it may not correctly enumerate a replacement 39RTMCAN module, so confirming firmware compatibility before installation is essential. Similarly, the CAN Bus termination resistors and cable connectors at both ends of the CAN segment must be intact — a missing or damaged termination is one of the most common causes of communication errors after a module swap.

For plants running mixed analog and digital I/O in the same ET 200 CAN station, the analog output modules and digital I/O modules sharing the same station bus should be inspected for age-related wear, particularly if the station has been in continuous service for more than ten years. Replacing the 39RTMCAN as part of a broader station refresh — rather than as a single emergency repair — reduces the risk of a second unplanned outage shortly after the first repair.

On the controller side, the SIMATIC S7-300 CPU or S7-400 CPU hosting the CAN master interface card must have a compatible hardware configuration block in STEP 7 or TIA Portal. If the project was originally built in STEP 7 Classic and the plant is considering a migration to TIA Portal V17 or later, the 39RTMCAN replacement is a natural checkpoint to also update the hardware catalog entries and GSD files for the entire ET 200 CAN station.

Plants that use SIMATIC WinCC or a third-party SCADA system for temperature trend monitoring should verify that the tag addresses mapped to the 39RTMCAN channels remain unchanged after the module swap. In most cases, because the CAN node address and slot position are preserved, no SCADA reconfiguration is needed — but this should be confirmed in the FAT (Factory Acceptance Test) checklist before returning the line to production.

Where the existing Pt100 RTD sensors and their field wiring are being retained, a 3-wire or 4-wire connection check with a calibrated resistance decade box prior to module installation will confirm that sensor lead resistance is within the module’s compensation range. This step is especially important in older installations where cable insulation degradation may have introduced leakage resistance that was previously masked by a less sensitive predecessor module.

For projects that require simultaneous replacement of the 24 VDC power supply module feeding the ET 200 CAN station, TOPNLMS can source compatible Siemens SITOP power supply units alongside the 39RTMCAN to consolidate the procurement into a single order and a single shipment, reducing logistics complexity and customs clearance time for international customers.

Finally, if the retrofit scope extends to replacing the programming cable or PC adapter used to connect a laptop to the S7 CPU for online diagnostics and module parameterization, ensure the adapter supports the MPI or PROFIBUS interface of the host CPU — the CAN Bus segment itself is not directly accessible from a standard PC adapter and is managed through the CPU’s hardware configuration.

Retrofit Guidance FAQ

Q: Can I replace the 39RTMCAN without rewiring the RTD sensors?
A: In the vast majority of installations, yes. The 39RTMCAN uses a standard screw-terminal front connector compatible with 2-wire, 3-wire, and 4-wire RTD connections. As long as the existing front connector is undamaged, it can be unplugged from the old module and plugged directly into the replacement unit without touching the field wiring.

Q: Do I need to modify my STEP 7 or TIA Portal program after replacing the module?
A: If the replacement module is the same order number (39RTMCAN) and the slot position in the ET 200 CAN station is unchanged, no program modification is required. The hardware configuration block and I/O addresses remain valid. A download of the unchanged hardware configuration to the CPU is recommended to confirm the online/offline comparison is clean before restarting the process.

Q: What CAN Bus baud rate does the 39RTMCAN support?
A: The module operates at the baud rate configured for the ET 200 CAN station, which is set at the station head / bus coupler level. Common rates for SIMATIC ET 200 CAN installations are 125 kbps, 250 kbps, and 500 kbps. The replacement module inherits the station baud rate automatically — no separate baud rate setting is required on the module itself.

Q: Will the replacement module fit in the same cabinet space?
A: Yes. The 39RTMCAN follows the standard ET 200 CAN module form factor and occupies a single slot in the station rack. No cabinet modification, additional DIN rail space, or mounting hardware changes are needed.

Q: How do I verify the module is communicating correctly after installation?
A: After inserting the module and powering the station, use STEP 7 or TIA Portal to perform an online hardware comparison. The CPU should recognize the 39RTMCAN in its configured slot with no hardware fault (SF LED off). Check the diagnostic buffer for any CAN communication errors and verify that temperature values are updating correctly in the process image.

Q: What if my original 39RTMCAN was a refurbished or third-party unit that failed prematurely?
A: TOPNLMS supplies only units that pass our pre-shipment functional test protocol, which includes power-on verification, channel-level RTD simulation, and CAN Bus communication check. All units are shipped with a 12-month warranty covering functional failure from the date of shipment.

Warranty Assurance

Every Siemens 39RTMCAN module shipped by TOPNLMS is covered by a 12-month warranty from the date of shipment. Our warranty process is straightforward: if a module exhibits a functional failure within the warranty period under normal operating conditions, we will arrange a replacement shipment at no additional cost to the buyer. Dead-on-arrival (DOA) units are prioritized for same-week replacement dispatch.

Prior to shipment, each 39RTMCAN undergoes a documented pre-shipment inspection that includes visual inspection for physical damage, power-on functional test, RTD channel simulation across the supported sensor range, and CAN Bus communication verification. Inspection records are available upon request for customers with quality management system (QMS) requirements.

For procurement teams managing MRO (Maintenance, Repair & Operations) budgets, TOPNLMS offers consolidated invoicing, packing lists with part numbers and serial references, and export documentation suitable for customs clearance in major industrial markets. Standard lead time from order confirmation to shipment is 1–3 business days for in-stock units. Express air freight options are available for emergency breakdown situations.

After-sales technical support is available via email and phone for questions related to installation, parameterization, and compatibility verification. Our team has hands-on experience with SIMATIC ET 200 CAN system architecture and can assist with GSD file sourcing, firmware version queries, and commissioning checklists.

For volume orders or long-term supply agreements covering multiple 39RTMCAN units or related ET 200 CAN station components, please contact our sales team directly to discuss pricing, lead time commitments, and consignment stock arrangements.