Wire connections for the thermocouple/rtd module, How to connect a 4-wire rtd, How to connect a 3-wire rtd – Rockwell Automation 1794-IRT8XT/B TC/MV/RTD Input Module Installation Instructions Manuel d'utilisation
Page 3: Block transfer read and write
3
Publication 1794-IN050J-EN-P - January 2009
Identify RTD Wire Pairs
If the RTD wires are color-coded, the wires that are the same color are
connected together. If the wires are not color-coded, use an ohmmeter to
determine the pairs as explained below.
How to Connect a 4-wire RTD
If the 4-wire RTD wires are all different colors, use an ohmmeter to
determine which leads are connected together. One of the leads in each
pair is the compensation lead. Either lead of the pair can be the
compensation lead. Attach one pair to terminals L and - and the other pair
to + and H.
How to Connect a 3-wire RTD
If the 3-wire RTD wires are all different colors, use an ohmmeter to
determine which leads are connected together. Either lead of the pair can
be the compensation lead. Attach one lead of the pair to terminal L and
the other to +. Attach the single lead to -.
Refer to the following table.
Wire Connections for the Thermocouple/RTD Module
Terminal Base Unit Wiring Connections
Example of RTD and Thermocouple Wiring to a 1794-TB3G Terminal Base
Unit
Example of Millivolt Wiring to a 1794-TB3G Terminal Base Unit
Block Transfer Read and Write
The following block transfer read and write word bit information is
presented for experienced users only. Refer to the user manual, publication
formation on programming and configuring
your module.
Input Map (Read)
RTD
or TC
Channel
1794-TB3G, 1794-TB3GK, and 1794-TB3GS Terminal Base Units
High Signal
Terminal (H)
Low Signal
Terminal (L)
RTD Source
Current (+)
Signal
Return (-)
0
A-1
A-2
A-0
A-3
1
A-5
A-6
A-4
A-7
2
A-9
A-10
A-8
A-11
3
A-13
A-14
A-12
A-15
4
B-18
B-19
B-17
B-20
5
B-22
B-23
B-21
B-24
6
B-26
B-27
B-25
B-28
7
B-30
B-31
B-29
B-32
1
Terminals 16, 33, and 40…45 are chassis ground.
+
mV
1
2
1
3
2
1
1a
2
2a
1
2
1
2
2-wir e
3-wir e
4-wir e
Thermocouple
Millivolt
RTD
-
Type of Input
Connect The Following
H
L
+
-
Shield
1
RTD - 2-wire
1
2
RTD - 3-wire
3
1
2
RTD - 4-wire
1a
2a
1
2
Thermocouple
1
2
Millivolt
1
2
1
Shield can be connected to chassis ground terminals
16, 33, and 40…45.
Wire Number
Numbers 1, 1a, 2, 2a, and 3 are wire numbers of the sensor
used. For terminal numbers corresponding to H, L, +, -, refer to
Terminal Base Unit Wiring Connections below.
Input
CJC Sensor
+
Chassis
Ground
-
CJC
Tail
(1)
CJC1
C-37
C-38
C-39
A-5
(B-22)
CJC2
C-46
C-47
C-48
A-12
(B-29)
1
Terminals 37, 38, and 39, and 46, 47, and 48 are for cold
junction compensation (with 38 and 47 chassis GND).
Connect the tail of CJC1 to terminal 5 and CJC2 to terminal 12 if
channels 0…3 or 0…7 are configured for thermocouples.
Connect the tail of CJC1 to terminal 22 and CJC2 to 29 if channels
4…7 are configured for thermocouples.
Dec.
15
14
13
12
11
10
09
08
07
06
05
04
03
02
01
00
Oct.
17
16
15
14
13
12
11
10
07
06
05
04
03
02
01
00
Word 0
Channel 0 Input Data
Word 1
Channel 1 Input Data
Word 2
Channel 2 Input Data
Word 3
Channel 3 Input Data
Word 4
Channel 4 Input Data
Word 5
Channel 5 Input Data
Word 6
Channel 6 Input Data
Word 7
Channel 7 Input Data
Word 8
Overrange Alarm Bits (channel 0 = bit 8, etc.)
Underrange Alarm Bits (channel 0 = bit 0, etc.
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
34
Channel 0
Channel 1
24V dc
Supply
In
Gnd
Gnd
24V dc
Supply
Out
+V
COM
+V
COM
6 Chassis
Ground
for Shields
Connections for terminal Base 1794-TB3G shown
Chassis Gnd
Chassis Gnd
+
-
H
L
+
-
H
L
+
-
H
L
+
-
H
L
Channel 2
Channel 3
Channel 4
Channel 5
+
-
H
L
+
-
H
L
+
-
H
L
+
-
H
L
Channel 6
Channel 7
CJC
CJC
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15
0
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
34
1794-TB3G
0…15
34…51
16…33
A
B
C
4-W ir e R TD Channel 3
2-W ir e R TD Channel 1
3-W ir e R TD Channel 2
Attention: Keep exposed area of inner conductor as short as possible.
+
CJC
Thermocouple Channel 4
1
2
2
1
1
3
2
1
1a
2a
2
_
17
18 19
20
21
22
23
24
25 26
27
28 29
30
31
32 33
0
1
2
3
4
5
6
7
8
9
10
11 12
13
14
15
16
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
0
35
36
37
38
39
40
41
42
43 44
45
46 47
48
49
50 51
34
1794-TB3G
0 …15
34…51
16…33
A
B
C
Millivolt
Source
Millivolt
Source
Millivolt
Source
Millivolt
Source
+
+
+
+
_
_
_
_
Attention: Keep exposed area of inner conductor as short as possible