5. ma output functions, 5. ma output functions -14 – Yokogawa EXA SC202 2-Wire Conductivity Transmitter/Analyzer User Manual
Page 60
IM 12D08B02-01E
5-14 Parameter setting
5-5. mA output functions
Code 31
*OUTP.F For the SC202 the output may be chosen as linear to input, or configured in a
21 point table to a particular linearization. Enable the table setup in code 31,
and configure the table in code 35.
Code 32
*BURN
Diagnostic error messages can signal a problem by sending the output signals
upscale or downscale (21 mA or 3.6 mA when HART or distributor comm. is
non-used, 3.9 mA when HART or distributor comm. is used). This is called
upscale or downscale burnout, from the analogy with thermocouple failure
signaling of a burned-out or open circuit sensor. The pulse burnout setting
gives a 21 mA signal for the first
30 seconds of an alarm condition. After the “pulse” the signal returns to normal.
This allows a latching alarm unit to record the error. In the case of the EXA the
diagnostics are extensive and cover the whole range of possible sensor faults.
Code 35
*TABLE
The table function allows the configuration of an output curve by 21 steps
(intervals of 5%). The following example shows how the table may be
configured to linearize the output with a mA curve.
mA
1,000
800
600
400
200
0
CONDUCTIVITY (S/cm)
CONCENTRATION (%)
100
80
60
40
20
0
Output in %
100
80
60
40
20
0
0
5
10
15
20
25
Output in %
Fig. 5-1. Linearization of output
Example: 0-25% Sulfuric acid
Concentration Output function is done in de following order:
• Set *OUTP.F. (Service Code 31) to table
• Set the Concentration range in % (Service Code 55)
• Set table values (%output and Conductivity values) in *TABLE (Service Code 35)
Code
Output
4-20 mA
% H
2
SO
4
Service
code 55
mS/cm
Service
code 35
Default
mS/cm
0
4.0
0.00
0
0
5
4.8
1.25
60
50
10
5.6
2.50
113
100
15
6.4
3.75
180
150
20
7.2
5.00
218
200
25
8.0
6.25
290
250
30
8.8
7.50
335
300
35
9.6
8.75
383
350
40
10.4
10.00
424
400
45
11.2
11.25
466
450
50
12.0
12.50
515
500
55
12.8
13.75
555
550
60
13.6
15.00
590
600
65
14.4
16.25
625
650
70
15.2
17.50
655
700
75
16.0
18.75
685
750
80
16.8
20.00
718
800
85
17.6
21.25
735
850
90
18.4
22.50
755
900
95
19.2
23.75
775
950
100
20.0
25.00
791
1000
Table 5-3.