Siemens SIMATIC S7-200 System Manual page 441

Table A-27 Configuring the Thermocouple Module DIP Switches
Switches 1,2,3
SW1, 2, 3 SW1, 2, 3
1 2 3 4* 5 6 7 8
* S t DIP * Set DIP switch 4 it h 4
to the 0 (down) position. to the 0 (down) position.
Switch 5
SW5
1 2 3 4 5 6 7 8
Switch 6
SW6
1 2 3 4 5 6 7 8
Switch 7
SW7
1 2 3 4 5 6 7 8
Switch 8
SW8
1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8
Thermocouple Type
J (Default)
K
Configuration
T
↑1 -- On On
↑1
E
↓0 -- Off
↓
R
S
N
+/--80mV
Open Wire Detect
Direction
Upscale
(+3276.7 degrees)
Co gu at o Configuration
↑1 -- On O
↑1
Downscale
↓0 -- Off
(--3276.8 degrees)
Open Wire Detect
Enable
Enable
Configuration
↑1 -- On
↓0 -- Off
↓
Disable
Temperature Scale
Celsius (_C)
Configuration Configuration
↑1 -- On
Fahrenheit (_F)
↓0 -- Off
Cold Junction
Cold junction
compensation enabled
Configuration
↑1 -- On
↓0 -- Off Off
↓0
Cold junction
compensation disabled
Technical Specifications
Setting Description
000 Switches 1 to 3 select the thermocouple type
(or mV operation) for all channels on the (or mV operation) for all channels on the
001
module. For example, for an E type, p ,
thermocouple SW1 = 0, SW2 = 1, SW3 = 1. S
010
011
100
101
110
111
Setting Description
0 0 indicates positive on open wire
1 indicates negative on open wire
1
Setting Description
0 Open wire detection is performed by injecting
a 25 µA current onto the input terminals. The
open wire enable switch enables or disables
the current source. The open wire range
check is always performed, even when the
current source is disabled. The EM 231 current source is disabled The EM 231
1
Thermocouple module detects open wire if the
input signal exceeds approximately ±200mV.
When an open wire is detected, the module
reading is set to the value selected by the
Open Wire Detect.
Setting Description
0 The EM 231 Thermocouple module can report
temperatures in Celsius or Fahrenheit. The
Celsius to Fahrenheit conversion is performed
i inside the module. id th d l
1
Setting Description
0 Cold junction compensation must be enabled
when you are using thermocouples. If cold
junction compensation is not enabled, the
conversions from the module will be in error
because of the voltage that is created when because of the voltage that is created when
1
the thermocouple wire is connected to the
module connector. Cold junction is
automatically disabled when you select the
±80mV range.
Appendix A
yp ,
S S
p
427