Allen-Bradley 5069-IY4 Compact 5000 RTD/Thermocouple Input

Four universal analog inputs including RTD and thermocouple

The Allen-Bradley 5069-IY4 is a Compact 5000 universal analog input module with four differential channels. A channel can be set for voltage, 0 to 20 mA or 4 to 20 mA current, resistance and RTD measurement, or thermocouple and millivolt inputs, which lets a single module cover temperature probes and process transmitters. It communicates with the controller through the Compact 5000 backplane and returns IEEE 32-bit floating point data.

The data sheet lists thermocouple types B, C, D, E, J, K, L (TXK/XK), N, R, S and T with ITS-90 linearization, and RTD types including 385 and 3916 platinum, nickel and copper elements.

Technical specifications

Temperature measurement details

For a thermocouple, the module needs cold junction compensation. Two thermistors, type Measurement Specialties 10K3A1A, are embedded in the 5069-RTB14CJC terminal block, or they can be wired to a 5069-RTB18 block. Local CJC accuracy is ±0.3 °C. If at least one thermocouple is connected, the data sheet requires the 5069-RTB14CJC-SPRING or 5069-RTB14CJC-SCREW terminal block.

RTD inputs use 600 µA excitation in 3-wire mode and 100 µA in 2-wire mode, with a maximum wire impedance of 25 ohms for the specified 3-wire accuracy. Calibrated accuracy is 0.100 percent of full scale at 25 °C, and total unadjusted error over the full temperature range is 0.300 percent for RTD and thermocouple modes.

Power, series and related modules

The module draws 75 mA of MOD power and 100 mA of SA power at 18 to 32V DC and dissipates up to 2.1 W. It has one module status indicator, four I/O status indicators and two CJC status indicators. The 5069-IY4K is the conformal-coated version. For eight voltage and current channels without temperature inputs, see the 5069-IF8.

Planning channels on a mixed-signal module

Because each of the four channels on the 5069-IY4 is configured on its own, one module can serve a small skid that has, for example, two RTD bearing temperatures, one thermocouple on an exhaust and one 4 to 20 mA pressure transmitter. Group signals with care, however: the inputs are not isolated from each other, so loops that are referenced to different grounds or that come from separately powered field devices may need external isolators. Where a project has many transmitters and only a few temperature points, it is usually cleaner to put the current loops on the 5069-IF8 and keep the IY4 for temperature work.

Choose the terminal block at the design stage. As soon as any channel on the module is wired to a thermocouple, the CJC version of the RTB is required, so ordering the plain 5069-RTB18 for a module that later gains a thermocouple point is a common cause of site delays.

Wiring and commissioning steps

• Use shielded copper cable within the wire range in the table, land the shield at one end only according to your plant earthing practice, and keep the cable away from drive and motor power wiring.
• For 3-wire RTDs, run three conductors of the same size and length so that lead resistance cancels, and stay within the 25 ohm wire impedance limit.
• Use thermocouple extension cable of the matching type all the way to the CJC terminal block; a short run of copper in between creates an extra junction and a reading error.
• Set the input type, range, filter and alarm limits for each channel in the programming software, download, and check every reading against a calibrator or a reference probe before handing the loop over.

Troubleshooting readings

A channel that jumps between values often points to a shield or earthing problem or to power cable running alongside the signal cable. A thermocouple that reads a few degrees off on every channel usually indicates a CJC issue, so check the CJC status indicators and the terminal block type first. An open-circuit RTD or thermocouple will show on the I/O status indicator for that channel; check the field terminations and the sensor before suspecting the module. Keep the screw RTB tightened to the torque in the table, as loose terminals on RTD circuits add resistance and cause drift.

Panels in Omani and GCC plants

The module is rated up to 60 °C, but control panels standing in the sun on Omani sites can exceed that inside without shading or cooling, so check the internal panel temperature during the hottest part of the year. A rising panel temperature also changes the conditions at the cold junction, which is one more reason to keep thermocouple terminations away from heat sources inside the enclosure. In coastal plants and in areas with fine airborne dust, the conformal-coated 5069-IY4K is the version to consider, and filter mats on panel fans should be cleaned on a regular schedule.

Documents and quotation

The Rockwell Automation Compact 5000 I/O specifications, publication 5069-TD001, are attached. See our PLC and I/O cards catalogue for CompactLogix controllers and related modules. Confirm the exact catalog number, series letter and firmware or hardware revision on the product label, and the compatibility with your existing system, before ordering. Stock and lead time are confirmed at quotation.