Specifications
65 Publication 1794-SG002D-EN-P - May 2012
Section
 1.4
Select a FLEX I/O Terminal Base Unit
Step 3 – Select:
the appropriate terminal base unit for your module and system
Each FLEX I/O module requires a terminal base unit that snaps onto the DIN 
rail to the right of the I/O adapter. The terminal bases provide terminal 
connection points for the I/O wiring and plug together to form the backplane. 
They are available with screw, clamp, or spring terminations.
The following table is a comparison of general specifications for each FLEX I/O 
terminal base unit. For compatibility with FLEX I/O modules, see TableDigital 
I/O Module Summary on page16.
Common Terminal Base Characteristics
Current Capacity, max Wire Size Dimensions
(HxWxD)
10 0.34…2.1 mm
2
 (22…14 
AWG) solid or stranded 
copper wire rated at 75 °C 
(167 °F) or greater, 1.2 mm 
(3/64 in.) insulation max
94 x 94 x 69 mm
3.7 x 3.7 x 2.7 in.
1794-TB37DS and 1794-TB62DS* 
(1)
127 x 94 x 69 mm
5.0 x 3.7 x 2.7 in
(1) Measured with expansion module installed.
General Specification Comparison
Catalog
(1)
Termination 
Type
Connections Used in Applications Current 
Capacity, 
max
Wiring 
Category
Purpose
1794-TB2 Cage clamp 16 I/O; 18 common; 2 +V Up to 132V AC/156V DC 10 2 A generic 2-wire version of the 
1794-TB3.
1794-TB3, 
1794-TB3K
(2)
16 I/O; 18 common; 18 +V Module 
dependent
Primarily intended for use with input 
modules when using 3-wire input 
proximity switches – can also be 
used with output modules.
1794-TB3S,
1794-TB3SK
Spring clamp A spring clamp version of the 
1794-TB3 – provides faster, simpler 
wire installation.
1794-TB32 Cage clamp 32 I/O; 8 common; 8 +V Up to 31.2V DC A 32-point version of the 1794-TB3 to 
be used with 32-point digital 
modules and the 1794-IB16D 
module.
1794-TB32S Spring clamp A spring clamp version of the 
1794-TB32.
1794-TB3G, 
1794-TB3GK
(2)
Grounded 
screw clamp
36 I/O; 2 common; 2 +V; 
10 chassis ground
A screw clamp terminal base unit 
with individual grounding used with 
certain analog modules.
1794-TB3GS, 
1794-TB3GSK
(2)
Grounded 
spring clamp
2 A spring clamp version of the 
1794-TB3G.










