What products are involved?

Rheonics inline viscometers and density meters, with the transmitter electronics SME-TR, SME-TRD, and SME-DRM.


What is the purpose of this article?

To explain how to connect each wire of the sensor cable to the correct terminal on the SME electronics and how to safely disconnect the cable if needed.


1. Overview

Rheonics inline viscometers and density meters are connected to the transmitter electronics (SME-TR, SME-TRD, SME-DRM) using a sensor cable.


The wiring depends on the sensor probe, and each SME is labeled with the wiring variant to use. The SME-DRM uses Variant A or B; the SME-TR and SME-TRD use Variants C and D, which follow the same wiring as A and B with the grounding on the terminal inside the housing [1], [2]. Section 2 shows how to find the variant and how to connect each wire. For the SME housings themselves, see Rheonics sensor electronics SME Drawings and 3D Models. For the wiring of your sensor, always check the operator manual that comes with your sensor.


Two SME-DRM units on a DIN rail, wired as Variant A (left) and Variant B (right): the 24V DC power cable (1), the sensor cable (2), and the green-yellow ground wires running to the ground terminal block beside the SME

Figure 1. SME-DRM wiring examples, Variant A (left) and Variant B (right): 1 power (24V DC), 2 sensor cable


2. Wire Color and Terminal Assignment

The wiring depends on the sensor probe. The lower label on the side of the SME shows which wiring variant to use (Figure 2) [1], [2].


Side of an SME-DRM with two labels: the paired sensor and SME serial numbers above, and the wiring variant, Variant-A, below

Figure 2. SME side labels: paired serial numbers (top) and wiring variant (bottom)


Connect each wire from the sensor cable to the terminal listed for your wiring variant in Table 1. In Variant B, wires 3 (green) and 4 (yellow) of the sensor cable go to ground instead of the SME, so SME terminals 3 and 4 stay empty. Terminal 0 goes to ground in both variants.


Wire ColorTerminal #, Variant ATerminal #, Variant B
Red88
Blue77
Pink (Rose)66
Grey55
Yellow4Ground
Green3Ground
Brown22
White11
Black (ground)00

Table 1. Sensor Cable Wire Color and Terminal Assignment, Variants A and B


Rheonics SME wiring diagram: sensor cable wires red to white on terminals 8 to 1, the black ground wire on terminal 0, and the cable shield to ground

Figure 3. Sensor wiring, Variant A


The only difference between the two variants: in Variant B, the green and yellow wires (wires 3 and 4) run to ground, and SME terminals 3 and 4 stay empty (crossed out in Figure 4).


Rheonics SME wiring diagram, Variant B: terminals 3 and 4 not used, the yellow and green wires and the black ground wire to ground, all other wires as in Variant A

Figure 4. Sensor wiring, Variant B


The SME-TR and SME-TRD use Variants C and D: the same wiring as Variants A and B (use those columns of Table 1), with the grounding on the terminal inside the housing. For these variants and for grounding, check the operator manual that comes with your sensor.


3. Cable and Crimp Preparation

The wire ends are delivered with crimped sleeves (8 mm pin length, 1 mm pin diameter) [3], [4], [5]. The cable can be shortened, if necessary, but sleeves must always be crimped on the stripped ends before connecting.


Blue Rheonics sensor cable with 8 mm crimped sleeve prepared for connection to SME transmitter terminal block.

Figure 5. Crimped Sensor Cable


This procedure also applies to power cables, Modbus cables, and 4–20 mA signal cables.


4. Connecting the Wires

  1. Disconnect all power before making electrical connections [1], [2].
  2. Use the column for your wiring variant in Table 1 to identify the correct terminal for each wire.
  3. Insert the crimped end of the wire into the terminal until it clicks firmly into place.
  4. Gently tug the wire to ensure a secure connection.


Do not pull with excessive force. This may damage the terminal block.


Color-coded sensor wires being connected to the Rheonics SME transmitter terminal block mounted on a DIN rail.

Figure 6. Connecting wire in Rheonics SME


5. Disconnecting the Wires

To safely remove a wire from the terminal block:

  1. Disconnect all power before removing wires.
  2. Press the white tab for that terminal using a small flat screwdriver (Figure 7).
  3. While pressing the tab, pull the wire straight out with your other hand.
  4. Ensure the wire is fully released before removing the screwdriver.


Color-coded sensor wires being disconnected from the Rheonics SME transmitter terminal block mounted on a DIN rail.

Figure 7. Disconnecting wire in Rheonics SME


6. References

  1. Rheonics GmbH, Rheonics SRV Inline Viscometer Manual, DocID SRV-G1-OP-2606, Jun. 2026.
  2. Rheonics GmbH, Rheonics SRD Inline Density and Viscosity Meter Manual, DocID SRD-G1-OP-2606, Jun. 2026.
  3. Rheonics, "Wire preparation for SME-DRM(Din Rail Mount)," Rheonics Support. [Online]. Available: https://support.rheonics.com/en/support/solutions/articles/81000408391. [Accessed: Sep. 23, 2026].
  4. Rheonics, "Wire preparation for SME-TR/TRD (Outdoor Mount)," Rheonics Support. [Online]. Available: https://support.rheonics.com/en/support/solutions/articles/81000410179. [Accessed: Sep. 23, 2026].
  5. Rheonics, "Wire preparation for Rheonics EX sensor," Rheonics Support. [Online]. Available: https://support.rheonics.com/en/support/solutions/articles/81000410683. [Accessed: Sep. 23, 2026].