Siemens Simatic S7-300 - M72166-Xxx00) to an Isolated AI

Analog Modules
4-63
Programmable Logic Controllers S7-300 Module Data
A5E00105505-03
Table 4-45 Ordering Data of the Comparison Point
Recommended Compensating Box
Order number
Reference junction with integrated power supply
unit, for rail mounting
Auxiliary power 220 VAC
110 VAC
24 VAC
24 VDC
Connection
to thermocouple Fe-CuNi Type L
Fe/Cu Ni Type J
Ni Cr/Ni Type K
Pt 10% Rh/Pt Type S
Pt 13% Rh/Pt Type R
Cu/Cu Ni Type U
Cu/Cu Ni Type T
Reference temperature 0 C
M72166-

B1
B2
B3
B4
1
2
3
4
5
6
7
00
Connecting to the comparison point (Order No. M72166-xxx00)
If all thermocouples connected to the inputs of the module have the same
comparison point, you compensate as follows:
M+
M–
M+
M–
Backplan
e
bus
ADC
M
L+
Compensating leads
(same material as
thermocouple)
Copper
wire
COMP
–
/M
ANA
COMP
+
Thermoco
uples
13
Auxiliary power
+
–
The terminals for the
compensating wire
must be short-
circuited!
Output (Cu wires)
89
1112
–
+
SIEMENS
M72166-
Logic
Figure 4-25 Connection of Thermocouples with Comparison Point (Order No. M72166-xxx00) to an
Isolated AI