Overview
The Siemens MultiRanger 100 (formerly Milltronics) is an ultrasonic level measurement controller used in tanks, sumps, wet wells, and similar process applications. It exposes a Modbus RTU interface on a 6-pin RJ11 jack (port #1) that is intended for direct connection to a PC running SIMATIC PDM (Process Device Manager). When commissioning, calibrating, or troubleshooting a MultiRanger 100 in the field, SIMATIC PDM is the supported engineering tool: it reads and writes parameters, allows you to save and restore device configurations, performs loop tests, and displays device diagnostics in a standardized view.
This guide consolidates the documented Siemens procedure for commissioning a MultiRanger 100 from a PC using SIMATIC PDM over Modbus RTU, including the special RS232-to-RJ11 interconnection cable (commonly called a "dolphin" cable), the relevant parameter indices on the device (P770 and P772), and the resolution of the most common installation issue: a missing Device Description (DD) in the SIMATIC PDM device catalog.
Prerequisites
Before you begin, gather the following items:
- Siemens MultiRanger 100 controller with the firmware version that supports Modbus RTU on RJ11 port #1.
- PC running a Microsoft Windows operating system supported by your installed version of SIMATIC PDM. The PC must have either a built-in RS232 (COM) port or a tested USB-to-RS232 serial adapter that exposes a standard DB9 male connector.
- SIMATIC PDM installed on the PC. Verify the version in PDM via Help → About SIMATIC PDM; this affects which device catalog is compatible.
- RS232-to-RJ11 serial cable (Siemens "dolphin" cable). This can be ordered from your Siemens representative as a Milltronics accessory cable, or hand-built using the wiring table in this article.
- MultiRanger 100 device catalog entry for SIMATIC PDM. This is delivered on the SIMATIC PDM Device Catalog CD, or as a free download from Siemens Industry Online Support.
- MultiRanger 100 manual (parameter reference for P770 and P772). The manual for the current product family is available on the Siemens support portal.
Hardware: The RS232-to-RJ11 Dolphin Cable
The MultiRanger 100's Modbus port is a 6-pin RJ11 jack located on the underside of the unit and labeled as port #1. PCs do not natively speak this connector, so an adapter cable is required. Siemens provides this as the RS232-to-RJ11 "dolphin" cable, identifiable by its molded DB9 female connector on one end and a 6-position RJ11 plug on the other.
If you need to build or verify the cable, the typical interconnection used by Milltronics/Siemens accessories is:
| DB9 (PC side) | Signal | RJ11 (MR100 side) |
|---|---|---|
| Pin 2 | RD (Received Data from PC → MR100 TX) | Pin 4 (RJ11) |
| Pin 3 | TD (Transmitted Data from MR100 RX → PC) | Pin 5 (RJ11) |
| Pin 5 | Signal Ground | Pin 2 (RJ11) |
The cable is a straight-through, point-to-point RS232 link. No hardware handshaking (RTS/CTS/DTR/DSR) is required by the MultiRanger 100 Modbus port; the device operates with TX, RX, and ground only.
Connection procedure
- Power down the MultiRanger 100.
- Plug the RJ11 end of the dolphin cable into port #1 on the MR100 until the latch clicks.
- Connect the DB9 end to an available COM port on the PC (or to your USB-to-RS232 adapter).
- Power the MR100 back up. The device will be in its out-of-the-box Modbus state and ready to communicate on address 1.
MR100 Communication Parameters
The MultiRanger 100 stores its serial-communication behavior in parameter indices P770 and P772. New units ship from the factory pre-configured for Modbus RTU communication, so you normally do not have to change anything to start a PDM session.
| Parameter | Description | Default value | Meaning |
|---|---|---|---|
P770 #1 |
Communication protocol selection | 3 |
Modbus RTU on the RJ11 port |
P772 |
Baud rate index | 115.2 |
115 200 bit/s (highest standard Modbus RTU baud) |
| Modbus address | Slave address of the device | 1 | Standard default; can be changed if multiple devices share the bus |
To verify the values from the front panel of the MR100:
- Enter programming mode on the device.
- Navigate to
P770, then to index#1. Confirm the value reads3. - Navigate to
P772and confirm it reads115.2. - Note the Modbus address shown on the communications page (typically
1).
P770 #1 = 1 for Dolphin protocol on the older PC interface), change it back to 3 for Modbus RTU before attempting PDM communication. The wrong protocol index is the most common cause of "no response" when the cable and PDM are configured correctly.Installing the SIMATIC PDM Device Catalog
SIMATIC PDM does not know how to talk to a MultiRanger 100 until the matching Device Description (DD) files are loaded into the device catalog. The DD is installed either from the SIMATIC PDM Device Catalog CD (delivered with the original SIMATIC PDM media kit) or from the latest downloadable catalog.
Option A — Install from the Device Catalog CD
- Insert the SIMATIC PDM Device Catalog CD into the PC's optical drive.
- Allow the installer to auto-run, or navigate the CD manually and execute
setup.exefrom the catalog directory. - Follow the prompts to install the full device catalog. This registers hundreds of device DDs at once, including the MultiRanger 100.
- When installation completes, restart SIMATIC PDM and the SIMATIC Manager if applicable.
Option B — Download the latest catalog
- Open SIMATIC PDM Device Catalog update — Siemens Support entry 31239837.
- Download the latest catalog archive appropriate for your SIMATIC PDM version.
- Extract the archive to a local folder.
- Start SIMATIC PDM, choose Options → Manage Device Catalog, and point the wizard at the extracted folder.
- When prompted "The selected source does not contain any device CDs", the path is wrong or the archive was extracted into a parent directory that does not contain the device-DD tree. Re-extract fully and select the folder that contains the individual device folders.
"Device description could not be loaded. Please install it in the SIMATIC Manager using 'SIMATIC PDM Manage Device Catalog' or reinstall SIMATIC PDM."
it means SIMATIC PDM cannot find the DD on the path it is searching. The reliable fix is to install the complete device catalog CD, not to load DDs one at a time. Loading the full catalog avoids missing references between the MultiRanger DD and its companion HART/Modbus DDs.
Configuring SIMATIC PDM for MultiRanger 100
Once the catalog is installed, configure the PC side of the link.
- Launch SIMATIC PDM.
- Open the Network view (default after first launch).
- Insert a new Modbus network from the menu or the right-click context menu.
- Open Properties on the Modbus network object and confirm:
- Interface: COMx (select the COM port your cable or USB adapter is using).
- Baud rate: 115 200 bit/s.
- Parity / Data bits / Stop bits: Even / 8 / 1 (typical Modbus RTU default) or None / 8 / 1, depending on the exact MR100 firmware. Match what the device is configured for.
- Response timeout: 1000 ms is a safe starting value for a point-to-point PC link.
- Click Apply, then OK.
Adding the MultiRanger 100 to the Modbus Network
- In the Network view, right-click the Modbus network object and choose Insert New Object → Device.
- From the device catalog list, locate Siemens MultiRanger 100 (it appears in the Modbus device tree once the catalog is installed).
- Select the device, confirm the insertion, and open its Properties.
- Set the Modbus address to match the value reported by the MR100 (typically
1for a new unit). - Save the configuration.
- Double-click the device icon to open the online view. SIMATIC PDM will attempt a Modbus RTU poll to the MR100.
When the poll succeeds, the device's online parameters populate. You can now read every parameter on the MR100, change values (for example, the level calibration parameters), download a configuration to the device, or upload the running configuration back to PDM as a backup.
Verification and Commissioning
After a successful connection, walk through these checks to confirm the link is healthy and the data you see is trustworthy:
- Online compare: Open the Device → Compare dialog. The online view should match the offline project without differences. Any difference indicates a parameter the device is holding that the project does not yet have.
- Read diagnostic buffer: Open Device → Diagnostics. Confirm there are no active faults related to the transducer or the serial port.
- Loop test: Use Device → Simulation to force the analog output to a known value (for example, 4 mA and 20 mA). Verify the control system sees the correct current. Exit simulation mode before leaving site.
- Upload to PG/PC: Perform a full Upload to PG/PC and save the resulting binary or XML parameter file in the project archive. This is your recovery point if the device is later misconfigured.
- Parameter printout: Generate a PDF parameter printout via File → Print for the commissioning record.
Troubleshooting Matrix
| Symptom | Likely cause | Resolution |
|---|---|---|
| "Device description could not be loaded" when inserting a Modbus device | DD not installed in SIMATIC PDM catalog | Install the full SIMATIC PDM Device Catalog CD, or download entry 31239837 and re-run Manage Device Catalog |
| "The selected source does not contain any device CDs" | Path pointed at wrong folder level or archive not fully extracted | Re-extract the catalog archive completely and point Manage Device Catalog at the folder that contains the individual device sub-folders |
| No response / timeout on COM port | Wrong COM port, wrong baud rate, or wrong Modbus address | Verify COM port in Windows Device Manager, set baud to 115 200, verify address matches MR100 setting; check P770 #1 = 3
|
| Garbled Modbus responses | Baud rate or parity mismatch between PDM and MR100 | Match PDM network properties to the MR100's P772 value; confirm parity is even or none as per device config |
| PDM connects but parameter values are wrong/stale | Offline project out of sync with running device | Run Upload to PG/PC and re-diff against the offline database |
| Communication works then drops intermittently | Loose RJ11 latch, damaged cable, or USB-RS232 adapter power saving | Re-seat the RJ11 plug; replace the dolphin cable; disable USB selective suspend on the COM adapter |
| MultiRanger 100 entry missing from device list after catalog install | Catalog installed for a different SIMATIC PDM major version | Download the catalog that matches the installed SIMATIC PDM version; major PDM versions (V8, V9, V10) require their own catalog |
Field-Proven Tips
- Always commission the MR100 with the transducer already installed and the tank in its normal operating condition. Empty/half-full tanks during commissioning produce misleading echo profiles.
- Before powering the MR100, verify that the dc-bus and analog-output terminals are not connected to any active loop. Hot-swapping the RJ11 cable while the device is in Modbus RTU polling can interrupt a frame and force a re-init on the next poll.
- Save a copy of the working parameter file on the engineering laptop and another on the project server. The MR100 has no internal removable media; the only record of the running configuration is what you save.
- If the PC cannot lock onto the link at 115 200 bit/s on the first try, drop to 19 200 bit/s (
P772 = 19.2) and re-poll. Long dolphin cables, low-grade USB adapters, and elevated EMI environments can all force a lower baud for stable communication. - When commissioning multiple MR100 units on the same bench, give each a unique Modbus address. Two devices with address 1 on the same COM port will collide and both will appear offline.
Standards and Reference Material
- Siemens Application Guide AG112504 — Connecting the Modbus MultiRanger/HydroRanger devices to SIMATIC PDM — the canonical reference for this exact procedure.
- Siemens Industry Online Support entry 31239837 — SIMATIC PDM Device Catalog updates — source of the latest downloadable catalog covering the MultiRanger 100 DD.
- MODBUS Application Protocol Specification V1.1b3 (Modbus Organization) — defines the RTU framing, CRC, and exception codes that the MR100 implements.
- EIA/TIA-232-F — the RS232 electrical standard that the dolphin cable implements between the PC DB9 and the MR100 RJ11.
FAQ
What cable do I need to connect a MultiRanger 100 to a PC for SIMATIC PDM?
Use an RS232-to-RJ11 serial cable, also known as the Siemens "dolphin" cable. It connects the PC's DB9 COM port to the MultiRanger 100's RJ11 port #1. Only TX, RX, and ground are wired; no hardware handshaking is required. If the PC has no RS232 port, use a tested USB-to-RS232 adapter.
What are the default Modbus RTU communication parameters on a new MultiRanger 100?
Out of the box, a new MR100 ships with P770 #1 = 3 (Modbus RTU mode), P772 = 115.2 (115 200 bit/s), and Modbus address 1. These values allow a direct connection to SIMATIC PDM with no parameter changes on the device.
How do I fix the "Device description could not be loaded" error in SIMATIC PDM?
The error means the MultiRanger 100 Device Description is not installed in the SIMATIC PDM device catalog. The reliable fix is to install the complete SIMATIC PDM Device Catalog CD, or to download the latest catalog from Siemens Support entry 31239837 and run Manage Device Catalog against the fully extracted folder. Single-device DD imports often fail because of missing companion DD references; the full catalog avoids that.
Can I commission the MultiRanger 100 without the SIMATIC PDM Device Catalog CD?
Yes. The catalog is available as a free download from the Siemens Industry Online Support entry 31239837. Download the version that matches the installed SIMATIC PDM major version (for example, SIMATIC PDM V9 requires the V9 catalog), extract it fully, and add the folder in Manage Device Catalog.
What if the MultiRanger 100 does not respond on Modbus even with the correct cable and parameters?
Verify P770 #1 is set to 3 (Modbus RTU), confirm the COM port number in PDM matches Windows Device Manager, and lower the baud rate to 19 200 bit/s as a test. Also check that the Modbus address in PDM matches the device (default 1). If the device was previously configured for the legacy Dolphin protocol, change P770 #1 back to 3 before retrying.