Hach-Lange SI794 P User Manual

DOC023.52.90115

si794 P

pH

4-Wire Transmitters

USER MANUAL

October 2008, Edition 1

© HACH LANGE GmbH, 2008. All rights reserved.
Printed in Germany

Return of products under warranty

Please contact our Service Team before returning a defective device.
Ship the cleaned device to the address you have been given. If the device
has been in contact with process fluids, it must be decontaminated/
disinfected before shipment. In that case, please attach a corresponding
certificate, for the health and safety of our service personnel.

Disposal

Please observe the applicable local or national regulations concerning
the disposal of “waste electrical and electronic equipment”.

Table of contents

Intended use ............................................................................5

Safety information .................................................................. 6

Overview of si794 P ............................................................... 11

Assembly ................................................................................12

Package contents ................................................................................ 12

Mounting plan ..................................................................................... 13

Pipe mounting, panel mounting ...................................................14

Installation and connection ..................................................16

Installation instructions .................................................................... 16

Terminal assignments ........................................................................ 16

pH wiring examples ........................................................................... 18

Protective wiring of relay outputs ................................................ 20

Interface and navigation ...................................................... 22

User interface........................................................................................ 22

Display ..................................................................................................... 23

Operation: Keypad ................................................................24

Safety functions ....................................................................25

Sensocheck, Sensoface sensor monitoring ...............................25

GainCheck device self-test ............................................................... 25

Automatic device self-test ............................................................... 25

Hold mode ...........................................................................................26

External activation of HOLD mode ...............................................27

Configuration ......................................................................... 28

Menu structure of configuration ................................................... 29

Overview of configuration steps ...................................................30

Output 1 .................................................................................................32

Output 2 .................................................................................................40

Temperature compensation ............................................................ 46

Calibration mode ................................................................................ 48

3

Alarm settings ...................................................................................... 50

Limit function .......................................................................................52

Switchover of parameter sets (manual) ...................................... 60

External switchover of parameter sets ........................................ 61

Default settings of parameter sets ...............................................63

Parameter set, individual settings ................................................. 64

Calibration ............................................................................. 66

pH calibration ....................................................................................... 67

Automatic calibration with Calimatic ......................................... 70

Manual calibration ..............................................................................72

Data entry of premeasured electrodes ....................................... 74

Product calibration ............................................................................ 76

Redox calibration ................................................................................78

Temp probe adjustment ................................................................... 80

Measurement .........................................................................80

Diagnostics functions ........................................................... 81

Controller functions ..............................................................84

PID controller ........................................................................................84

Pulse length / pulse frequency controller.................................. 86

Error messages (error codes) ................................................87

Calibration error messages ..............................................................89

Operating states .................................................................... 91

Sensoface ...............................................................................93

Appendix ................................................................................95

Product line and accessories........................................................... 95

Specifications ........................................................................................ 96

Buffer tables ........................................................................................102

Glossary ................................................................................110

Contact information ............................................................114

Limited warranty .................................................................116

Index .....................................................................................119

4

Intended use

The si794 P transmitter is used for pH/mV, ORP, and temperature
measurement in industry, environment, food processing, and
sewage treatment.
The sturdy molded enclosure can be attached to a panel, wall, post
or pipe railing. The optional hood provides protection against
direct weather exposure and mechanical damage.
The transmitter can easily be replaced and it accepts commercially
available electrodes with a nominal zero point at pH 7 and ISFET
sensors. It provides a second current output for temperature
measurement, a PID controller (making use of the relay contacts),
and a universal power supply for 24 ... 230 V AC/DC.
For CIP applications, you can switch between two parameter sets.

5

Safety information

Be sure to read and observe the following!

The device has been manufactured using state of the art technology
and it complies with applicable safety regulations.
When operating the device, certain conditions may nevertheless
lead to danger for the operator or damage to the equipment.
Therefore, please read this entire manual before unpacking, setting
up, or operating this equipment. Pay particular attention to all
danger and caution statements.

Precautionary labels

Read all labels and tags attached to the instrument. Personal injury
or damage to the instrument could occur if not observed. A symbol,
if noted on the instrument, will be included with a danger or
caution statement in the manual.

This symbol, if noted on the device, references the
instruction manual for operation and/or safety
information.

This symbol, when noted on a product enclosure or
barrier, indicates that a risk of electric shock and/or
electrocution exists.

This symbol, when noted on the product, identifies
the location of a fuse or current limiting device.

This symbol, when noted on the product, identifies
the location of the connection for Protective Earth
(ground).

6

This symbol, when noted on the product, identifies
a risk of chemical harm and indicates that only indi­viduals qualified and trained to work with chemicals
should handle chemicals or perform maintenance
on chemical delivery systems associated with the
equipment.

This symbol, when noted on the product, identifies
the presence of a noxious substance and a risk of
chemical harm. Only individuals qualified and
trained to work with chemicals should handle
chemicals or perform maintenance on chemical
delivery systems associated with the equipment.

This symbol, when noted on the product, indicates
the presence of devices sensitive to electrostatic
discharge (ESD) and indicates that care must be
taken to prevent damage with the equipment.

Electrical equipment marked with this symbol may
not be disposed of in European public disposal
systems after 12 August of 2005. In conformity with
European local and national regulations (EU Directive
2002/96/EC), European electrical equipment users
must now return old or end-of life equipment to the
Producer for disposal at no charge to the user.

Note:

You can obtain instructions on the correct disposal
of all (marked and unmarked) electrical products
that have been supplied or manufactured by Hach­Lange from your local Hach-Lange sales office.

7

Signal words for hazard information

This manual uses signal words to mark safety information.
They are used alone or in combination with a safety symbol.
If multiple hazards exist, this manual will use the signal word
(Danger, Caution, Note) corresponding to the greatest hazard.

DANGER Indicates a potentially or imminently

hazardous situation which, if not avoided,
could result in death or serious injury.

CAUTION Indicates a potentially hazardous situation

that may result in minor or moderate
injury.

Important Note Information that requires special

emphasis.

Note Information that supplements points in

the main text.

8

General safety information

Do not use or install the si794 transmitter in any manner other
than that which is specified in this manual.

Important Note

Commissioning must only be carried out by trained personnel.
Whenever it is likely that protection has been impaired, the device
shall be made inoperative and secured against unintended
operation.
The safety of the transmitter may be impaired if any of the
following conditions have occurred:

visible damage•
failure to operate properly•
storage above 70 °C for prolonged periods•
exposure to severe transport stresses•

If any of these conditions have occurred, return the device to the
manufacturer for recertification.

Note

Before commissioning it must be proved that the transmitter may
be connected with other equipment.

Important Note

Working with chemical samples, standards, reagents, and waste
presents potential hazards.
The device must only be operated by trained personnel authorized
by the operating company.
The manufacturer is not liable for any damages caused by process­related risks known to the operating company.

9

Information on how to prevent electrostatic discharges (ESD)

Important Note

The sensitive electronic components in the device can be damaged
by static electricity. This can impair device performance and even
lead to a complete failure of the device.
Before connecting a sensor, for example, you should discharge any
static electricity buildup from your body. To do so, you can touch an
earth-grounded metal surface such as the chassis of a device or a
metal conduit or pipe.

10

Overview of si794 P

Glass
electrode

Reference
electrode

Auxiliary
electrode

RTD

RTD

Shield

ISFET
+3V

ISFET

-3V

HOLD

HOLD/
CONTROL

CONTROL

1

pH / mV /
temp
input

2

3

E

Output 1

Output 2

R1

D

R2

9

10

11

12

13

14

+ Output 1

– Output 1/2

+ Output 2

Relay 1

Relay 1/2

Relay 2

C

± 3 V

4

for ISFET
sensor

Alarm

15

16

Alarm

Alarm

5

Clean / PSet 2

Clean

HOLD

6

input

7

Control

8

input

Power

17

18

19

20

Clean / PSet 2

Power

Power

11

Assembly

11

10

9

8

76 5

4

1

2

3

Package contents

Check the shipment for transport damage and completeness.
The package should contain:

• Front unit

• Rear unit

• Bag containing small parts

• User manual

• Specific test report

1 Jumper (2 x)
2 Washer (1 x), for conduit

mounting: Place washer between

enclosure and nut
3 Cable tie (3 x)
4 Hinge pin (1 x), insertable from

either side
5 Enclosure screw (4 x)

Fig.: Assembling the enclosure

12

6 Sealing insert (1 x)
7 Rubber reducer (1 x)
8 Strain relief (3 x)
9 Filler plug (3 x)
10 Hex nut (5 x)
11 Sealing plug (2 x),

for sealing in case of wall mounting

Mounting plan

144

144

15

42

84

80

32

21

43

105

27

72

6,2

12

3

4

Fig.: Mounting plan – All dimensions in mm!

1 Strain relief (3 x)
2 Strain relief or 1/2“ conduit

opening, ø 21.5 mm (2 x)
Conduit hardware not included!
3 Knockout for pipe mounting
(4 x )
4 Knockout for wall mounting
(2 x )

13

40 60

132

1

2

3
4

5

1

132165

173

1

Pipe mounting, panel mounting

1 Protective hood (LZY485) - if required
2 Hose clamp with worm gear drive to DIN 3017 (2 x)
3 Pipe-mount plate (1 x)
4 For vertical or horizontal posts or pipes
5 Self-tapping screw (4 x)

Fig.: Bracket kit (LZY483) – All dimensions in mm!

Fig.: LZY485 protective hood for wall and pipe mounting

– All dimensions in mm!

14

1

2

3

45

max. 25

78 27

1...22

1 Screw (4 x)
2 Gasket (1 x)
3 Control panel
4 Span piece (4 x)
5 Threaded sleeve (4 x)

Fig.: Panel mounting kit (LZY484) – All dimensions in mm!

15

Installation and connection

Installation instructions

Caution!

Any work on the electrical installation may only be undertaken by
experienced and qualified personnel in accordance with the applicable
local safety regulations.

• Always disconnect power to the device when making any electrical

connections!

• Be sure to follow the instructions in the user manual!

• Only connect the power supply when all internal wirings have been

completed and the system is correctly grounded!
When using an external voltage supply, always connect a ground-fault
circuit interrupter (tripping current max. 30 mA) between mains and
controller system! A ground-fault circuit interrupter is not required
when safety extra-low voltages (24 V DC supply via rechargeable
batteries or 24 V DC/AC supply through an isolation transformer)!
When operating the system outdoors, connect a surge voltage
protection between mains and controller system!
The terminals are suitable for single wires and flexible leads up to

2.5 mm² (AWG 14). Attach end ferrules to the leads.

Terminal assignments

Danger of electric shock!

Fig.: si794 P terminal assignments

16

4

3

1 ESD shield covering the signal inputs
(Screw off for assembly)

Note:

The cable shield must end under the ESD shield.
(Cut lines if required)

2 Terminals for temperature probe and outer shield
3 Terminals for electrode
4 Power supply connection

1

2

Fig.: Information on installation, rear side of device

17

pH wiring examples

Example 1:

pH measurement with
monitoring of glass electrode

Jumper
across
2 and 3

Cable shield –

Do not ground!

Color

Top 68

Assign-

ment

Jumper

cable

Coax
core

Coax
(shield)

Terminal

1 Glass

elec­trode

2 Ref.

elec­trode

(

3

2-3)

C Shield Green/

D RTD Red Green Red
E RTD White White White

SMEK
cable

Trans­parent
(coax
core)

Black
(coax
shield)

yellow

8350.0

Trans­parent
(coax
core)

Black
(coax
shield)

18

Example 2:

pH measurement with
monitoring of glass and
reference electrode

Terminal

Assign-

1 Glass

electrode

2 Reference

electrode
3 SG Blue
C Shield
D RTD Red
E RTD White

Cable shield –

Do not ground!

ment

Color

8350.3

8350.4

8350.5

Transparent
(coax core)

Black
(coax shield)

19

1

2

3

1

2

3

Protective wiring of relay outputs

Protective wiring of relay contacts

Relay contacts are subject to electrical erosion. Especially with
inductive and capacitive loads, the service life of the contacts will
be reduced. For suppression of sparks and arcing, components
such as RC combinations, nonlinear resistors, series resistors, and
diodes should be used.

Typical AC applications
with inductive load

1 Load
2 RC combination, e.g. RIFA PMR 209
Typical RC combinations
for 230 V AC:
Capacitor 0.1µF / 630V,
Resistor 100 ohms / 1 W
3 Contact

20

Typical protective wiring measures

A: DC application with inductive load
B: AC/DC applications with capacitive load
C: Connection of incandescent lamps

A1 Inductive load
A2 Free-wheeling diode, e.g. 1N4007 (Observe polarity)
A3 Contact
B1 Capacitive load
B2 Resistor, e.g. 8 Ω / 1 W at 24 V / 0.3 A
B3 Contact
C1 Incandescent lamp, max 60 W / 230 V, 30 W / 115 V
C3 Contact

Warning!
Make sure that the maximum ratings of the relay contacts are
not exceeded even during switching!

21

Interface and navigation

The si794 transmitter user interface contains a display, indicators,
and keys for navigation and menu selection.

User interface

Use the arrow and enter keys to scroll through the menu and
change settings. Use the indicators to identify which mode the
transmitter is in.

6

5

4

3

2

1

Fig.: si794 user interface

1 Calibration key 7 Wash mode indicator
2 Congure key 8 Conguration mode indicator
3 Measure mode indicator 9 Up arrow key
4 Calibration mode indicator 10 Right arrow key
5 Alarm indication
6 Display

11 Enter key

7

8

9

10

11

22

Display

Interface and navigation

4.3 Display

Figure 11 identifies all of the possible icons and symbols that may be

seen in the si792 transmitter display.

The gure below identies all of the possible icons and symbols
that may be seen in the si794 transmitter display.

Fig.: si794 display

1 Passcode 13 Secondary display
2 Temperature 14 Alarm mode
3 4–20 mA/HART output 15 Manual temperature on
4 Limit values 16 Calibration mode
5 Alarm 17 Hold mode active
6 Sensocheck: Sensor error 18 Hourglass (waiting indication)
7 Calibration active 19 Measure mode active
8 Calibration interval 20 Calibration complete

8 Parameter display 21 Calibration: zero or rst point
10 Enter prompt 22 Calibration: second point
11 Conguration mode
12 Main display

23 Sensofaces

23

Operation: Keypad

Start, end calibration

Start, end configuration

Select digit position
(selected position blinks)

Edit digit

• Calibration:

Continue in program sequence

• Configuration: Confirm entries,

next configuration step

• Measuring mode: Display output current

Cal Info: Display of offset (zero point) and slope

Error Info: Display of last error message

24

+

Start GainCheck device self-test

Safety functions

Sensocheck, Sensoface sensor monitoring

Sensocheck continuously monitors the sensor and its wiring.
Sensocheck can be switched o (Conguration).

Sensoface provides information on the electrode condi­tion. The oset (zero point), slope, and response time
during calibration are evaluated. The three Sensoface
indicators provide the user with information about wear
and required maintenance of the electrode.

GainCheck device self-test

A display test is carried out, the software version is displayed,
and the memory and signal transfer are checked.

Start GainCheck device self-test:

Automatic device self-test

The automatic device self-test checks the memory and signal
transfer. It runs automatically in the background at xed intervals.

+

25

Safety functions

Hold mode

Display:

The Hold mode is a safety state during conguration and calibra­tion. Output current is frozen (Last) or set to a xed value (Fix).
Alarm and limit contacts are disabled.
If the calibration or conguration mode is exited, the transmitter
remains in the Hold mode for safety reasons. This prevents un­desirable reactions of the connected peripherals due to incorrect
conguration or calibration. The measured value and “HOLD” are
displayed alternately. The transmitter only returns to measuring
mode after enter is pressed and 20 seconds have passed.

Conguration mode is also exited automatically 20 minutes
(timeout) after the last keystroke. The transmitter returns to
measuring mode.

Timeout is not active during calibration.

Response of output signal:
Last: The output current is frozen at its last value.

Recommended for short conguration procedures.
The process should not change decisively during con­guration. Changes are not noticed with this setting!

Fix: The output current is set to a value that is noticeably

dierent from the process value in order to signal the
control system that the transmitter is being worked at.

26

External activation of HOLD mode

The Hold mode can be activated from outside by sending a signal
to the Hold input (e.g. from the process control system).

Power supply

Hold

12...24 V AC/DC

6

input

si794

7

Process control system

Hold active Hold inactive
10 ... 30 V AC/DC 0 ... 2 V AC/DC

Alarm

The alarm delay is congurable.
During an error message the alarm LED blinks or lights.

Error messages can also be signaled by a 22 mA output current.
The alarm contact is activated by alarm or power failure,
see also Pg 50.

The alarm LED on the front panel can be congured as follows
HOLD o: Alarm: LED blinks
HOLD on: Alarm: LED on. HOLD: LED blinks

27

Configuration

In the Configuration mode you set the device parameters. The device can
store two different parameter sets and switch between them. Sensor data and
“Clean/Pset2” output are edited in parameter set 1 only. They are valid for
both parameter sets.

Configuring

Parameter set 1

Configure:

Press conf.

Enter mode code “1200”:
Edit parameter set 1 with and , con­firm/proceed with enter.

Parameter set 2

Configure:
“88” appears in the
display.

Enter mode code “1288”:
Edit parameter set 2 with
firm/proceed with enter.

and , con-

The output current is frozen

Hold

During
configuration
the device
remains in the
Hold mode.

Input errors

HOLD icon

(at its last value or at a preset fixed
value, depending on the configurati­on), limit and alarm contacts are inac­tive. The controller is in the configured
state, Sensoface is off, mode indicator
“Configuration” is on.

The configuration parameters are
checked during the input. In the
case of an incorrect input “Err” is dis­played for approx. 3 s. The incorrect
parameters cannot be stored. Input
must be repeated.

End End with conf. The measured value

and Hold are displayed alternately,
“enter” flashes. End Hold mode with
enter . The display shows the measu­red value. The output current remains
frozen for another 20 s (HOLD icon on,
“hourglass” flashes).

28

Menu structure of conguration

The conguration steps are assigned to dierent menu groups.
Use the arrow keys to jump between the individual menu
groups. Each menu group contains menu items for setting the
parameters.
Press enter to access a menu item. Use the arrow keys to edit
values. Press enter to conrm/save the settings.
To return to measurement, press conf and then enter.

Select menu
group

Menu group Code Display

Output 1 o1.

Menu item 1

Menu item 2

Menu item ...

Output 2 o2.

Temperature
compensation

Calibration mode CA.

Alarm settings AL.

Relay rL.

Cleaning contact
PSet 2 selection

tc.

Cn.

...

Select
menu item

Previous
menu
group:

29

Overview of conguration steps

Code

Menu

Output 1

out1

o1.

Select process variable
Select electrode type

Select current range
Enter current start

Enter current end

Time averaging filter

22 mA signal in the case of error

Signal response during HOLD

Enter fixed value

Output 2

out2

o2.

Select temperature unit

Select temperature probe

Select current range

Enter current start
Enter current end

Time averaging filter

22 mA signal for temp error

Signal

response

Enter fixed value

Temperature compensation

tc.

tc.

Temp detection during meas
Temp detection during cal
Enter TC process medium

Calibration mode

CAL

CA.

Select calibration mode

Enter cal timer interval

during HOLD

Choices Default

PH/ORP PH
(GLAS EL/FEt EL ) GLAS EL
0-20 mA/4-20 mA 4-20 mA
xxxx 00.00 pH
xxxx 14.00 pH
xxxx SEC 0 SEC
ON / OFF OFF
Last / Fix Last
xxx.x mA 021.0 mA

°C / °F °C
100 Pt/1000 Pt/30NTC/

8.55NTC/3000B 1000 Pt
0-20 mA/4-20 mA 4-20 mA
xxx.x 000.0 °C
xxx.x 0100.0 °C
0000 ... 0120 SEC) 0 SEC
ON / OFF OFF
Last / Fix Last
xxx.x mA 021.0 mA

Auto/man (man: xxx.x °C)
Auto/man (man: xxx.x °C)
xx.xx %/K 00.00%/K

BUF/MAN/DAT 06 BUF
xxxx h 0000 h

30