Electro-Chemical Devices (ECD) SMS22 - Manual (Page 23)

TC .333 %/°C
Isopot XXX.X mV
Equilib 11.98 pH
Dissoc 0.001 On
Temperature Compensation, no adjustment needed
Isopotential point, MANDITORY ENTRY
Equilibrium value for Sulfide ion dissociation, pKa
MUST BE ON, value varies with the pH according to the pKa
Noise filter 5
Set Up Channel 2 Menu
Settings
Settings
4mA 0.00 pH
20mA 14.00 pH
Contrast 5
3.4 OUTPUTS (4-20 mA Channels)
The SMS-22 has two 4-20 mA outputs. The Sulfide channel, mA1 is configured for 0-10 ppm Sulfide Ion,
although all values are configurable. (See Section 3.3.4 above) The second 4-20 mA output is configured
for 0-14 pH. The SMS-22 uses a Lascar DPM-742-BL Loop Powered indicator to convert the 4-20 mA1
output into ppm sulfide reading. This unit must be re-scaled whenever the 4-20 mA range is changed.
(See Appendix C)
3.4.1 Manual Mode (4-20 mA Hold Function)
The % Output values are displayed on the Home Screen for the S--
output, mA 1, and for the optional pH Output, mA 2. Manual
Mode is an output Hold function commonly used to freeze the
outputs during maintenance and calibration cycles. While in
Manual Mode the Output can be adjusted between 0 and 99.9%
using the CALIBRATE keys. This is very useful for troubleshooting
loop communication problems.
In the SMS-22 the outputs are configured to be under manual
mode control at all times except when the reading is taken. An “M” will be displayed in front of the %
Output value indicating the output is being held at the “Last Value”. The Output will remain frozen at
the last value until the next measurement cycle when the Manual Mode is switched off for 10 seconds
to acquire the next reading.
The mA outputs are only updated in the RUN cycle. The values are frozen when the SMS-22 is in the
CALIBRATE or PRIME cycles.
3.5 ALARM RELAYS
TheSMS-22 uses all four available relays to control the pumps and drain valves used in the SMS-22.
There are NO alarm relays available in the SMS-22.
SMS-22 Page 14