Chapter 5: sensor connections, 1 overview, 2 terminal block pinouts – Sensoray 2518 User Manual
Page 15: 3 sensor channels
Sensoray Model 2518/2519 Ethernet Smart A/D™
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Sensor Connections
Chapter 5: Sensor Connections
5.1 Overview
Sensors connect to the Smart A/D™ by means of
pluggable screw terminal blocks on the model 2509 base
board. In addition to the terminal blocks, the base board
also contains integral temperature sensors for
thermocouple reference-junction compensation.
5.1.1 Sensor Hot Insertion
Sensors may be electrically connected to and
disconnected from the terminal blocks, and terminal
blocks may be plugged onto and unplugged from the base
board without removing power from the base board.
5.2 Terminal Block Pinouts
All of the pluggable terminal blocks (TBs) that are used
for sensor terminations are located on the base board as
shown in Figure 10.
Figure 10: Sensor terminal blocks
Positions for up to eight sensor TBs are provided on the
base board. These TBs are referenced as TB1 through
TB8.
All eight of the TB positions are used on model 2519. In
the case of model 2518, only TB1 through TB4 are used,
even though all eight of the TB positions may be
populated.
Terminal block pin numbers are silkscreened onto the
board using “X.Y” notation, where X is the TB number
and Y is the pin number. For example, the silkscreened
legend “3.7” designates pin number 7 of TB3.
Each TB connects two sensors to the unit. Table 5 shows
the TB numbers and pin assignments for models 2518
and 2519. The bottom table row lists the TB numbers.
For any particular TB number in the bottom row,
examine the intersecting column to determine which
sensor channels connect to that TB.
Example:
Let’s examine the case of TB7. First, look across the
bottom row of Table 5 to find TB7. Now, looking up
the intersecting column, it can be seen that TB7 is used
to connect sensors to channels 4 and 5. Channel 4
occupies pins 1 to 5, which are designated “7.1” to
“7.5.” Channel 5 occupies pins 6 to 10, which are
designated “7.6” to “7.10.”
5.3 Sensor Channels
Each sensor channel provides five signals for interfacing
to a sensor: V+, V-, I+, I- and S. A sensor can have as
many as five connections to a channel, or as few as two.
5.3.1 Sense Terminals
Two of the channel signals, designated V+ and V-, are
universally used for all sensor types. These two signals
are, respectively, the positive and negative differential
voltage sense inputs.
Since the sense inputs accept differential signals, it is not
required for either of the two input signals to be at ground
potential. The Smart A/D™ digitizer measures only the
difference voltage across the two sense inputs.
Due to common-mode voltage (CMV) input constraints,
however, you must ensure that neither sense input, with
respect to system ground, exceeds the maximum input
CMV permitted by the Smart A/D™.
Table 5: Sensor terminal block pin assignments
P
in
N
o
.
F
u
n
c
.
Channel
1
V+
0
2
4
6
8
10
12
14
2
I+
3
V-
4
I-
5
S
6
V+
1
3
5
7
9
11
13
15
7
I+
8
V-
9
I-
10
S
TB:
5
6
7
8
1
2
3
4