What is a thermocouple?

A temperature sensor created by joining two dissimilar metals at one end. When the junction of the two metals is heated or cooled, a voltage is created that can be correlated back to the temperature.

What type of thermocouples do you read?

B, E, J, K, N, R, S, and T thermocouple types supported; the DT8871 automatically linearizes the measurements and returns the data as a 32-bit, floating-point temperature values.

What is an RTD?

An RTD is a resistance temperature detector, and is used to measure temperature by correlating the resistance of the RTD element with temperature. Most RTD elements consist of a length of fine coiled wire wrapped around a ceramic or glass core. The element is usually quite fragile, so it is often placed inside a sheathed probe to protect it. The RTD element is made from a pure material (i.e., platinum, nickel or copper) whose resistance at various temperatures has been documented. The material has a predictable change in resistance as the temperature changes; it is this predictable change that is used to determine temperature.

What RTDs do you measure?

TEMPpoint supports Pt100 (100 Ω Platinum), Pt500 (500 Ω Platinum), and Pt1000 (1000 Ω Platinum) RTD types using Alpha coefficients of 0.00385 (European) and 0.00392 (American) and 4-wire, 3-wire, or 2-wire configurations; you can mix and match RTD types across channels. The DT8872 automatically linearizes the measurements and returns the data as a 32-bit, floating-point temperature values.

Can you measure PRTs?

Yes, a PRT (platinum resistance thermometer) is a type of RTD that uses platinum as its element.

Are the analog input channels isolated?

Each channel has ±500 V galvanic isolation channel-to-channel and to the host computer to protect signal integrity.

What is galvanic isolation?

The principle of isolating functional sections of electrical systems so that charge-carrying particles cannot move from one section to another, i.e. there is no electrical current flowing directly from one input channel to the next.

What is the voltage input range?

Input range of ±75mV (±1.2500 V option). Larger voltage ranges can be made by using a voltage divider.

Can I vary the sample rate?

Yes, TEMPpoint supports an internal clock with a maximum sampling rate of 10 Samples/s. Use software to specify an internal clock source and a clock frequency between 0.000152590219 Hz and 10.0 Hz. When the continuous operation is started, all the channels specified in the channel list are read simultaneously at the specified clock frequency. The Measurement Application software enables you to change the sample rate to several common time intervals.

Does the digital input read TTL level signals?

Yes, TEMPpoint features eight, isolated, digital input lines. Digital inputs operate from +3 to +28 V DC, with a switching time of 2 ms maximum.

How much current does the digital output provide?

None. The digital output lines act as a solid-state relay. The customer-supplied signal can be ±30 V at up to 400 mA (peak) AC or DC. Switching time is 2 ms maximum. You can use the digital output lines to control solid-state or mechanical relays or high-current electric motors.

Are the digital I/O lines isolated?

The DT8871 temperature instrument includes channel-to-channel isolation of up to 250 V between digital I/O lines. If you require greater channel-to-channel isolation, use every other digital line. This reduces the number of digital I/O lines, but provides channel-to-channel isolation of 500 V (one channel can be +250 V while the adjacent channel can be –250 V).

Does TEMPpoint have traceability to NIST standards?

Yes. The TEMPpoint CJC channels are calibrated using an ASL F200 precision thermometer. This instrumentation used to calibrate TEMPpoint instruments is calibrated against a NIST traceable external reference.

What is the common mode rejection of the TEMPpoint?

The common mode rejection is specified at greater than 150 dB at 50Hz and 60 Hz.

How is TEMPpoint Calibrated?

Your TEMPpoint temperature instrument is factory-calibrated to meet or exceed its published specifications using standards traceable to NIST. A two-step calibration process is used. First, the A/D on each channel is calibrated for gain and offset; these values (including the zero point) are stored in ROM. Second, each CJC circuit is calibrated.

In addition, the DT8871 temperature instrument auto-calibrates on each power-up cycle to guarantee high-accuracy measurements. This process, also known as auto-zeroing, resets the zero point of each A/D. You can also auto-calibrate the instrument at any time (as long as acquisition is not in progress) using a software command. Refer to your software documentation for more information on the auto-calibration feature.

When is recalibration necessary?

While TEMPpoint instruments were designed to preserve high accuracy measurements over time, it is recommended that your instrument be recalibrated every year to ensure that it meets or exceeds specifications.  Recalibration must be performed by Data Translation. Please contact Data Translation at 508-481-3700, ext. 1323 (if you are in the USA) for information on TEMPpoint factory recalibration. If you are located outside the USA, call your local distributor for information; see our web site (www.datatranslation.com/company/offices/) for the name and telephone number of your nearest distributor.

Does this device have certification?

Each TEMPpoint instrument is factory calibrated and includes a Certificate of Calibration.

What is LXI (LAN eXtensions for Instrumentation)?

LXI is an instrumentation platform based on industry standard Ethernet technology designed to provide modularity, flexibility and performance to small- and medium-sized systems.  LXI modules are full-rack width, 1U tall or half-rack width, 1U or 2U tall. Signals enter and exit the module from its front panel while LAN (IEEE 802.3), power, and trigger cables are found on the back of the module. All modules are designed to be easily mounted in a standard 19" rack or stacked on the bench. For more information, please visit: http://www.lxistandard.org/about/faq/.

How do I attach TEMPpoint to a network?

To connect a TEMPpoint Instrument to the Ethernet network and/or your computer, do the following:

1. Make sure that you have attached a power supply to the module.
2. Attach one end of the supplied EP372 Ethernet cable to the LAN (Ethernet) port on the module.
3. Attach the other end of the Ethernet cable to the Ethernet network (LAN or WAN) through a router or hub. Or, create an ad hoc network with your computer using an Ethernet crossover cable.

The instrument automatically requests an Ethernet address from a DHCP server, if available, and a host name from a DNS server, if available. If these services are not available on the LAN, the TEMPpoint uses AutoIP to set up its TCP/IP configuration.

How do I locate my TEMPpoint Instrument on the LAN?

To access the web interface of your instrument, you must determine its IP address on your TCP/IP network. We recommend that you download and run the Eureka Discovery Utility from the Data Translation web site (http://www.datatranslation.com/cd/MEASURpoint/). This utility helps you locate or "discover" all LXI (Ethernet) instruments that are connected to your system and provides the following information about your instrument: the IP address, manufacturer, model number, serial number, and version of the firmware that is running on your instrument. In addition, you can use this utility to configure Windows firewall settings and update the firmware for your LXI instrument.

Note: The TEMPpoint web pages require Java version 6, update 5 or greater for proper operation. Go to www.java.com to download or upgrade Java. In addition, ensure that your internet browser is configured to enable JavaScript (sometimes listed as Active Scripting).

How many users can access the TEMPpoint Instrument on the LAN?

At any instant, up to 8 clients can access the TEMPpoint instruments concurrently using the web interface.

Up to 12 additional clients can access the TEMPpoint instruments concurrently using SCPI. Of these, 4 can be VXI-11 clients, which use the VISA ::INSTR resource to access the instrument.

At this time, the web and SCPI interfaces cannot be "locked;" therefore, one client can change the configuration of the instrument that another client is accessing. However, you can optionally lock the VXI-11 interface using the VISA APIs viLock/viUnlock; this prevents other VXI-11 clients (including VXI-11 discovery) from accessing the instrument.

Who has control of the TEMPpoint Instrument on the LAN?

Anyone with access to the TEMPpoint instrument can control it, change settings, etc. The LXI standard does not currently include a mechanism for resource management. When the standard is established, it will be implemented.

What software support is available?

The following software is available:

• MEASURpoint Framework – Ready-to-measure application that allows you to acquire thermocouple, RTD, and/or voltage data from multiple instruments simultaneously, record data to disk, display the results in both a plot and a digital display, and read a recorded data file. Once it is installed, you can access this application from the Windows Start menu by clicking Programs > Data Translation, Inc > MEASURpoint Framework.
• DtxMeasurement IVI-COM driver – Provides access to the functionality of VOLTpoint, TEMPpoint, and MEASURpoint instruments through a COM server. The IVI-COM driver works in any development environment that supports COM programming, including Measure Foundry®, Visual Basic®, Visual C#® .NET, The MathWorks™ MATLAB®, Agilent VEE Pro, National Instruments' LabVIEW™ or LabWindow, and others. Once it is installed, you can access the IVI-COM driver, example programs, and documentation from the IVI standard root directory location.
• Eureka Discovery Utility – This utility helps you locate or "discover" all LXI (Ethernet) instruments that are connected to your system and provides the following information about your instrument: the IP address, manufacturer, model number, serial number, and version of the firmware that is running on your instrument. In addition, you can use this utility to configure Windows firewall settings and update the firmware for your Data Translation LXI instrument.
• SCPI Support – SCPI (Standard Commands for Programmable Instruments) is a universal programming language for electronic test and measurement instruments, based on the IEEE 488.1 and IEEE 488.2 standards. VOLTpoint, TEMPpoint, and MEASURpoint LXI instruments comply with the SCPI language and implement the IEEE-488.2 STD status structure. You can issue SCPI commands over VISA or sockets. This installation includes the SCPI Programmer's Manual for LXI Measurement Instruments, the documentation for your instrument, as well as example programs written in Visual C# and Visual C++.
• Measurement Instrument Calibration Utility – The calibration utility allows you to calibrate a VOLTpoint, TEMPpoint, or MEASURpoint instrument in the field. Using this utility, you can revert to the factory calibration for any or all channels, or revert back to the last user calibration values, if desired. In addition, this utility generates a report that lists the starting and ending calibration values for each channel, allowing traceability. Since each instrument consists of 48 individual instruments, great care must be taken to ensure that proper warm-up times are followed and precise calibration equipment is used. The calibration utility ships with a comprehensive help file that describes the required equipment and calibration procedure, including warm-up times, for each instrument model.
• Measurement Instrument Documentation – Installs the user's manuals for TEMPpoint™, VOLTpoint™, and MEASURpoint™ instruments. Each manual describes how to install and set up your instrument, verify that the instrument is working properly, features and capabilities of the instrument, and detailed specifications and troubleshooting information.

Can I use TEMPpoint with Linux?

Yes, via SCPI commands over a TCP/IP socket.

Can TEMPpoint be calibrated in the field?

The Measurement Instrument Calibration Utility allows you to calibrate a VOLTpoint, TEMPpoint, or MEASURpoint instrument in the field. Using this utility, you can revert to the factory calibration for any or all channels, or revert back to the last user calibration values, if desired. In addition, this utility generates a report that lists the starting and ending calibration values for each channel, allowing traceability. Since each DT measurement instrument consists of 48 individual instruments, great care must be taken to ensure that proper warm-up times are followed and precise calibration equipment is used. The calibration utility ships with a comprehensive help file that describes the required equipment and calibration procedure, including warm-up times, for each instrument model.