Technical data
Publication 1794-2.1 - January 2000
124 24V dc RTD Input Module Cat. No. 1794-IR8 FLEX I/O and FLEX Integra Product Data
Data Type
RTD Type
ATTENTION
!
Total current draw through the terminal base unit is
limited to 10A. Separate power connections to the
terminal base unit may be necessary.
RTD
Channel
1794-TB3, -TB3S, -TB2 Terminal Base Unit
High Signal
Terminal
Low Signal
Terminal
Signal
Return
1
Shield
Return
0 A-0 A-1 B-17 B-18
1 A-2 A-3 B-19 B-20
2 A-4 A-5 B-21 B-22
3 A-6 A-7 B-23 B-24
4 A-8 A-9 B-25 B-26
5 A-10 A-11 B-27 B-28
6 A-12 A-13 B-29 B-30
7 A-14 A-15 B-31 B-32
24V dc Common 16 thru 33
+24V dc power 34 thru 51 (34 and 51 for TB2)
1 When using a 2-wire RTD, jumper the signal return to the low signal terminal.
RTD
Channel
1794-TB3T or -TB3TS Terminal Base Unit
High Signal
Terminal
Low Signal
Terminal
Signal
Return
Shield
Return
1
0 A-0 A-1 B-17 C-39
1 A-2 A-3 B-19 C-40
2 A-4 A-5 B-21 C-41
3 A-6 A-7 B-23 C-42
4 A-8 A-9 B-25 C-43
5 A-10 A-11 B-27 C-44
6 A-12 A-13 B-29 C-45
7 A-14 A-15 B-31 C-46
24V dc Common 16, 17, 19, 21, 23, 25, 27, 29, 31 and 33
+24V dc power 34, 35, 50, and 51
1 Terminals 39 to 46 are chassis ground.
0123456 78 9101112131415
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
33
16
34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49
51
50
1794-TB3, -TB3S, -TB2, -TB3T, or -TB3TS
0 1 2 3 4 5 6 7 8 910 11121314 15
0-15
16-33
34-51
A
B
C
30233
34 and 51
for TB2
Example of 2-, 3- and 4-wire RTD Wiring to a 1794-TB3 or -TB3S Base Unit
0-15
16-33
34-51
A
B
C
30234
0123456789101112131415
1794-TB3
2-Wire RTD
3-Wire RTD
4-Wire RTD
Clip or tieback
4th lead.
ATTENTION: Keep exposed area of inner conductor as short as possible.
jumper low to signal ret
For pure resistance measurements, tie each side of resistor to “high” and “low”
terminals. Then jumper the “low” (odd numbered) terminal to signal return (com).
Word Description
Write
word 0
Module Data Type
Bit 01 00
00
o
C (default) or resistance (in Ω)
01
o
F
1 0 Bipolar counts scaled between -32768 and +32767
1 1 Unipolar counts scaled between 0 and 65535
Word Description
Write
word 1
RTD Type - Range
Bit 03020100Channel 0
0000Resistance (default)
0001No sensor connected - do not scan
0010100W Pt ∝ = 0.00385 Euro (-200 to
+870
o
C)
0011100W Pt ∝ = 0.003916 U.S. (-200 to
+630
o
C)
0100200W Pt ∝ = 0.00385 Euro (-200 to
+630
o
C)
0101500W Pt ∝ = 0.00385 Euro (-200 to
+630
o
C)
0110Reserved
0111
10Ω Copper (-200 to +260
o
C)
1000
120Ω Nickel (-60 to +250
o
C)
1001
100Ω Nickel (-60 to +250
o
C)
1010
200Ω Nickel (-60 to +250
o
C)
1011
500Ω Nickel (-60 to +250
o
C)
1100Reserved
Bit 07 06 05 04 Channel 1 - see bits 00-03, word 1
11 10 09 08 Channel 2 - see bits 00-03, word 1
15 14 13 12 Channel 3 - see bits 00-03, word 1
Write
Word 2
Bit 03 02 01 00 Channel 4 - see bits 00-03, word 1
07 06 05 04 Channel 5 - see bits 00-03, word 1
11 10 09 08 Channel 6 - see bits 00-03, word 1
15 14 13 12 Channel 7 - see bits 00-03, word 1
0-15
16-33
34-51
A
B
C
30235
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
1794-TB3T
2-Wire RTD
3-Wire RTD
4-Wire RTD
Clip or tieback
4th lead.
A
TTENTION: Keep exposed area of inner conductor as short as possible.
Example of 2-, 3- and 4-wire RTD Wiring to a 1794-TB3T Base Unit
Temp and resistance data is returned with an implied decimal point. For example
a temp data of 1779 is 177.9°. Resistance data of 2034 is 203.4Ω.