53A-225 – Thermocouple Input Card
OPT 1V – Add VXIbus Compatibility

• 10 input channels (expandable to 240 channels using 53A-339)
• High Accuracy
• Types J, K, R, S, T, B, and E thermocouples can be intermixed
• Electronic cold junction compensation and linearization to degrees C or F
• Programmable set-points
• Can be operated as a microvoltmeter

The Thermocouple Card provides 10 input channels with isothermally protected ice point compensation and linearity correction for types J, K, R, S, T. B, and E thermocouples. Temperature (or voltage) measurementsmay be taken at a maximum of 15 readings per second (12.5 per second for 50 Hertz).

Three modes of operation are provided for: 1) manual – a channel number is selected under program control and readings taken from that channel; 2) scanning – a scan list is defined for more than one channel and readings are taken in the order specified by the scan list; and 3) limit check scanning – high and low limits are preprogrammed for each channel to be automatically scanned. An interrupt will be generated if an out-of-limits condition is detected, freeing the system controller for other tasks. Input channels may be added or deleted, and/or limits may be changed, without interrupting limit check scanning. In this last mode, either the channel number only, or the channel number and the actual measurement may be returned under program control in the event of an out of limit condition. In addition, the scan rate is programmed and maintained on-card, further freeing valuable system controller resources.

In all three modes, measurements may be returned in degrees Kelvin, Celsius, or Fahrenheit; or the Card may be programmed as a ten-channel scanning microvoltmeter with limit checking. Amplifier drift compensation may be updated automatically or, if the user chooses, manually under program control. Automatic reference junction temperature updates are also provided. In addition, the system controller can read the temperature of the reference junction, allowing the Thermocouple Card to be used to monitor ambient temperature inside the CDSbus 53/63 mainframe.

The resolution of the Thermocouple Card is 15°C (.27°F) worst case.  Total system accuracy is between 0.5 and 0.9°C, ±02% of the reading.

The screw terminals for the thermocouple wires are completely enclosed within an isothermal chamber in order to maintain the minimum possible temperature differential between the input connections and the thermistor used for ice point compensation. Access is provided through an easily removable, rubber gasketed cover plate that also provides strain relief for input thermocouple wires. The screw terminal assembly itself is removable to allow for quick connect and disconnect without disturbing the cable-to-screw connection.

Five LEDs provide Built-In-Test Equipment (“BITE”) for the Thermocouple Card. These LEDs indicate the selected channel in binary format as well as an error indication when an improper command is detected.

Types of Thermocouples: J, K, R, S, T. B, and E.

Number of Channels: Ten.
Expandable to 240 channels using 53A-339 Thermocouple Scanner Card.

Data Returned As:
ASCII Characters, base 10 decimal notation.

Manual, Scan, and Automatic Unit Check Scan.

Temperature: Centigrade, Fahrenheit. or Kelvin.

– 13.9 to 76.5 mV range,
– 9.7 to 21.2 mV range.

Input Configuration:
Two wires plus shield for each channel, each channel individually isolated.

Input Isolation:
±200V dc or peak ac between low and ground or any two channels.

Input Protection:
250V dc or 250V RMS across input terminals.

Input Connections: 3 screw terminals per channel located within isothermal chamber.
Accessed by removal of cover plate.

Reference Junction Compensation Accuracy: ±0.2°C from 0 to 50°C.

Common Mode Rejection: 120 dB at 50/60 Hz with 1 KOhm unbalance.
Normal Mode Rejection: 70 dB at 50/60Hz.

Reading Rate:
15 Reading/ Second, 60 Hz.
12.5 Readings/Second. SO Hz.
(For multiple cards, maximum system reading rate can be multiplied by the number of cards.)


Response Time: latest reading available immediately.

Automatic between 0.57 µV resolution range and 2.4 µV resolution range.

Autoranging Levels:
Uprange at 100% of sensitive range.
Downrange at =99% of sensitive range.

Temperature Coefficient ±(25 ppm ±2 µV)/°C

Open Circuit Detection: Reading of 99.999 returned when open circuit is detected.

Voltage. 0.57 µV for – 0.7 to 2l.l mV range. 2.4 µV for – 13.9 to 76.5 mv range.
Temperature, divide voltage resolution by voltage/temperature coefficient of thermocouple to be used.

Calibration Cycle: 12 months.

Programmed By: ASCII Characters.

Available Option:
OPT 1V. add VXIbus compatibility.