Watlow 942 User Manual

Series 942

User's Manual

TOTAL

CUSTOMER

SATISFACTION

1/4 DIN

Microprocessor-Based

Ramping Control

Watlow Controls

1241 Bundy Blvd., P.O. Box 5580, Winona, MN 55987-5580, Phone: [phone], Fax: [phone]

W942-XUMN Rev. R00	$10.00
June, 1995	Made in the U.S.A.

Supersedes:

W942-MA40-9305

Printed on Recycled Paper

2	WATLOW Series 985 User's Manual		Appendix

Page	Item			Contents
	Chapter 1
4	Starting Out With The Watlow Series 942-
4	General Description
5	Opening the 942	Figures, Tables, Charts
5	Set the DIP Switches	Page	Item		Figure
	Chapter 2	4	Series 942 Input & Output Overview		1
		5	How to Open the Series 942		2
6	How To Install And Wire The Series 942-	5	DIP Switch Location and Orientation		3
6	System Planning	6	Overview of the Series 942		4
6	Installation Information	8	Series 942 Faceplate Dimensions		5
7	Dimensional Information	8	Series 942 Panel Cutout Dimensions		6
8	Wiring The Series 942	8	Series 942 Sideview Dimensions		7
8	Sensor Installation Guidelines	9	120 VAC Power Wiring		8
9	Input Wiring	9	240 VAC Power Wiring		9
11	Output 1 Wiring	10	Thermocouple Wiring Diagram		10
15	Output 2 Wiring	10	RTD Wiring Diagram		11
17	Auxiliary Wiring	11	0 - 5 Process Input Wiring Diagram		12
20	System Wiring Example	11	4 - 20 Process Input Wiring Diagram		13
	Chapter 3	12	Solid State Relay, Output 1 Wiring		14
		12	DC (Open Collector) Output 1 Wiring		15
21	How To Use the Keys And Displays	13	6 Amp Mechanical Relay, Output 1 Wiring		16
	Chapter 4	13	4 - 20mA Process, Output 1 Wiring		17
		14	0 - 5VDC Process, Output 1 Wiring		18
22	How To Setup The Series 942	14	S.S. Relay, w/o contact supp., Output 1		19
22	Entering The Setup Menu	15	S.S. Relay, Output 2 Wiring Diagram		20
23	Setup Parameters	15	DC (open Collector), Output 2 Wiring		21
28	Operation Menu and Parameters	16	6A Mechanical Relay, Output 2 Wiring		22
	Chapter 5	16	S.S. Relay, w/o contact supp., Output 2		23
		17	Auxiliary Option 1, 1 - 6 Amp Relay		24
31	Programming the Seres 942	17	Auxiliary Option 2, 2 - 6 Amp Relays		25
31	Program Menu	18	Auxiliary Option 3, 6 Amp Relay/0-5ret.		26
32	Program Parameters	18	Auxiliary Option 4, 6 Amp Relay/4-20ret.		27
34	Running the Series 942	19	Auxiliary Option 5, None/0-5Retransmit		28
35	Resume a Profile	19	Auxiliary Option 6, None/4-20mA Retransmit 29
36	Event Outputs	20	System Wiring Example		30
37	Multiple Profiles	21	Series 942 Keys and Displays		31
37	Jumploops	22	Entering the Setup Menu		32
38	Programming a Ramping Profile	22	The Setup Menu		33
38	Running Your Profile	28	The Operation Menu		34
39	Editing Your Profile	31	The Program Menu		35
	Chapter 6	34	The Run Menu		36
		37	Guaranteed Soak Deviation Example		37
	How To Tune and Operate	42	Auxiliary Jumper Location		38
40	Tuning - Automatic and Manual	43	Deviation Alarm Example		39
42	Changing the Auxiliary Jumper Position	43	Alarm Display Examples		40
42	Using Alarms	44	Error Code Display Example		41
44	Error Code Messages & Actions	53	Differential Mode Filter Wiring		42
	Appendix 1	53	Common Mode Filter Wiring		43
		53	Combination Filter Wiring		44
46	Specification	54	The Calibration Menu		45
48	Model Number Information	55	Calibration Parameters		46
	Appendix 2
49	Installation Guidelines For Preventing Noise				Tables
51	Eliminating Noise	26	Input Ranges		1
52	Checking For Ground Loops	27	Setup MenuParameters/Description		2
52	Noise Suppression Devices Available…	30	Operation Menu Parameters/Description		3
53	Line Filtering Configurations For Controls	38	Series 942 Ramp and Soak Profile		4
	Appendix 3	39	Editing Your Profile, steps 4 - 7		5
54	Entering the Calibration Menu	52	Noise Suppression Device Ratings		6
56	Calibration Procedures	57	RTD Settings		7
64	Glossary
66	Index				Charts
67	Warranty/Returns	35	Master Step Chart		1

Appendix

WATLOW Series 985 User's Manual

3

Starting Out

Chapter 1

The Watlow Series 942,

A Microprocessor-Based Control

Single Input -

Type J, K, T, N, R, S, B, C or Pt2

Thermocouple, RTD or Process

RS-422A, RS423A (RS-232C compatible), or EIA-485 Optional Computer Interface

Figure 1 -

Series 942 Input and

Output Overview.

Dual Outputs-

PID or ON/OFF, User Selectable

Output 1

Heat or Cool

Output 1 Auto-tuning (Heat only)

Output 2

Heat, Cool or None

Dual Alarms/Events

Retransmit Output

(Up to 10 Slaves)

Process

Set Point

General Description

Welcome to the Watlow Series 942, a 1/4 DIN microprocessor-based ramping temperature control. It is a single input, dual output, auto-tuning control with 24 step program capability and easy fixed set point operation. The 942 accepts a Type J, K, T, N, R, S, B, C or Platinel 2 thermocouple, RTD, or process input. The primary output is heating or cooling, while the secondary output can be heating, cooling or none.

With the Series 942 you can select either PID or ON/OFF for Output 1 or 2. You can input a complete set of PID parameters for both outputs, including proportional band, reset/integral and rate/derivative. You can also select automatic tuning for Output 1 while in the heating mode. By setting either output's proportional band to zero, the Series 942 becomes a simple ON/OFF control with the switching differential selectable under the HYS Setup parameter.

Two optional auxiliary outputs may be alarms or events. An event is an ON/OFF mechanical relay output. Events are based on time, and can trigger peripheral equipment or processes. An optional retransmit output is offered in lieu of one of the auxiliary outputs. Select either retransmit of process variable or set point.

Operator-friendly features include automatic LED indicators to aid in monitoring and setup, as well as a calibration offset at the front panel. The Watlow Series 942 automatically stores all information in a non-volatile memory.

4

WATLOW Series 942 User's Manual

Getting Started, Chapter 1

Starting Out

How to Open the 942

Before going further, open the Series 942 and pull the control chassis from its case. Here's how:

The control chassis fastens to the case with a single standard screw located on the

!

LOCK

Three strip connector plugs, in the rear of the control chassis, feed power and signals through the back of the case to the terminal strips. These plugs will let go as you pull.

When removing the Series 942 control from its case, pull firmly but gently. When returning the control to the case, be sure you have the top up to match the plugs with the case. The 942 will not fit in the case upside down, but check to be sure it is oriented correctly. Press the unit in firmly, then turn the front panel screw clockwise to secure it. This insures proper electrical contact.

Figure 2 -

How to Open the Series 942.

! WARNING: The front panel screw turns 90° only. Do not apply excessive force or turn the screw more than 90°.

How to Set the DIP Switches

The Watlow Series 942 has a Dual In-line Package (DIP) switch inside the control on the A007-1954 circuit board (middle board). The location of the board and switch appear below. The switches are clearly numbered. When Switch #1 is ON, the Setup parameters can be viewed but not changed. When Switch #2 is ON, it provides battery backup of the Run parameters. When the control leaves the factory, both switches are OFF.

1 Hardware lockout of

1 Hardware Lockout of

Setup parameters

SETUP Parameters

22 Battery Disbackuphargeoforthe RunStorageparameters

(Factory default is OFF)

Control Chassis - Top View

Figure 3 -

DIP Switch Location

and Orientation.

NOTE:

The lithium battery has a life of approximately ten years. When the battery expires, Pout and Run are affected (see Chapters 4 & 5). Return the unit to the factory for a replacement.

Getting Started, Chapter 1

WATLOW Series 942 User's Manual 5

Installation

Chapter 2

How to Install and Wire the Series 942

NOTE:

Removing the Series 942 chassis from its case may make mounting easier.

System Planning

This chapter tells you how to install the Series 942. All mounting and wiring information is right here. Because Watlow controls are thoroughly tested and "burned in" before leaving the factory, the Series 942 is ready to install when you receive it.

But before you begin working, read through this chapter to gain an understanding of the entire installation. Consider sensor installation carefully. For detailed information you'll need to look at the noise reduction guidelines in the Appendix of this manual before making your panel cutout.

Installation Information

The Series 942 mounts in a panel cutout with two brackets, shipped with your control. These brackets hold the case against the front panel. The Series 942 behind-panel dimensions are 3.6" (90 mm) high by 3.6" (90 mm) wide by 6" (152 mm) deep. Figure 5 on the next page shows the dimensions of the front panel bezel. The 942 weighs 2.75 lbs. (1.25 kg) max.

For dimensional and mounting information, including the location of mounting brackets and size of the front panel cutout, see Figures 5 through 7 on the next page. Your panel's thickness can be from 0.06" (1.5 mm) to 0.25" (6.3 mm).

Installation Procedure

Follow this procedure to mount the Watlow Series 942 Temperature Control:

1.Make a panel cutout per the dimensions in Figure 6.

2.Remove the 942 from its case by turning the front panel screw 90° counterclockwise (CCW). Grip the bezel firmly and pull the control chassis out of the case.

!WARNING:

The front panel screw turns 90° only. Do not apply excessive force or turn the screw more than 90°.

!

3.Place the case in the cutout you just made.

4.Attach the mounting brackets either to the top and bottom, or to both sides of the unit.

5.Tighten the mounting brackets securely against your panel.

6.Insert the control chassis into its case and press the bezel to seat it. Turn the front panel screw 90° clockwise (CW) to lock the control in place. The hardware installation is complete. Proceed to the wiring section from here.

6 WATLOW Series 942 User's Manual

Install and Wire, Chapter 2

0.92" (23 mm)

3.81" sq.							Dimensions
(97 mm)

3.81" sq. (97 mm)

Figure 4 -

Series 942

Dimensions.

6.0" (152 mm)

Bezel

3.8" (97 mm)

Mounting Bracket	3.6" ± 0.015"

(90 mm ± 0.381)

3.622 to 3.653

3.62" to 3.65"

(92.00 to 92.79mm)

(92 to 93 mm)

Your Panel	Panel					Figure 5 -
						Series 942
Your Panel	Cutout					Panel Cutout
Thickness
Thickness:				3.62"	to 3.65"	Dimensions.
				3.622 to 3.653
	3.63" X 3.63"
0.06" to 0.25"				(92 to 93 mm)
	3.625 x 3.625			(92.00 to 92.79mm
0.06 to 0.25	(92.08 X 92.08 mm)
(1.52 to 6.35mm)	(92.08 x 92.08mm)
(1.524 to 6.35mm)	Nominal
k	NOTE:
	All dimensions in inches.

Install and Wire, Chapter 2	WATLOW Series 942 User's Manual	7

Power Wiring

NOTE:

For 50 or 60Hz operation, no adjustment or jumper placement is necessary.

How to Wire the Series 942

The Series 942 wiring is illustrated by model number option. Check the terminal designation sticker on the control and compare your model number to those shown here and to the model number breakdown in the Appendix of this manual.

Series 942 internal circuits appear "inside" the line drawing of the 942, while connections and terminal designations appear "outside" the line drawing. All outputs are referenced to a de-energized state. The final wiring figure is a typical system example.

When you apply power without sensor inputs on the terminal strip, the Series 942 displays "- - - -" in the Upper display, and Er7 in the Lower display. This error indicates an open sensor or A/D error. Remove power to the control and connect the sensor properly, see Page 10. All wiring and fusing must conform to the National Electric Code and to any locally applicable codes as well.

Figure 6 -

120 VAC Power

Wiring.

CAUTION:

To avoid potential electric shock, use National Electric Code (NEC) safety practices when wiring and connecting this unit to a power source and to electrical sensors or peripheral devices.

Figure 7 -

240 VAC Power

Wiring.

			Fuse
11					L1
12					L2
13					Earth Ground
		120 VAC

Fuse

10 L1

Fuse

12 L2

13		Earth Ground

240 VAC

Sensor Installation Guidelines

We suggest you mount the sensor at a location in your process or system where it reads an average temperature. Put the sensor as near as possible to the material or space you want to control. The sensor should be thermally insulated from the sensor mounting.

8

WATLOW Series 942 User's Manual

Install and Wire, Chapter 2

Input Wiring

Thermocouple Input
Model # 942A	- 1 _	_ _ - _ 000	942A - 3 _ _ _ - _ 000
942A	- 2 _	_ _ - _ 000	942A - 4 _ _ _ - _ 000

Figure 8 -

Thermocouple

Input Wiring.

+

7

9 -

You must use an isolated or ungrounded thermocouple, if an external device with a nonisolated circuit common is connected to the 4-20mA or 0 - 5VDC output.

Extension wire for thermocouples must be of the same alloy as the thermocouple itself to limit errors.

RTD, 2 or 3 Wire

Model # 942A - 2 _ _ _ - _ 000

942A - 3 _ _ _ - _ 000

	Jumper #5 to #6	Figure 9 -
	for 2-Wire RTD
4	4	2 or 3 wire RTD
		Input Wiring.
5	5
6	6

Long lead lengths create electrical resistance. There will be approximately +2° C input error for every 1Ω of lead length resistance, when using a two wire RTD. The resistance, when added to the resistance of the RTD element, will result in erroneous input to the instrument. To overcome this problem, use a three wire RTD sensor, which compensates for lead length resistance. When extension wire is used for a three wire RTD, all three extension wires must have the same electrical resistance. (i.e. same gauge, copper stranded).

Install and Wire, Chapter 2

WATLOW Series 942 User's Manual 9

Input Wiring

Figure 10 -

0 - 5VDC Process

Input Wiring.

NOTE:

When using a

0 - 5VDC process input, the input impedance is 100KΩ.

When using a process input such as 0 - 5VDC or 4 - 20mA, the rL and rH settings scale the display to match the measured range of the process signal.

An example of this is: A pressure transducer operates over a range of 0 - 300 PSI, delivering a 4 - 20mA output signal for this range. By setting rL = 0 and rH = 300, the Series 942 now displays a direct reading of pressure.

0 - 5VDC Process Input

Model # 942A - 2 _ _ _ - _ 000

942A - 3 _ _ _ - _ 000

1	+
						VDC
2
3
	-

Figure 11 -

4 - 20mA Process

Input Wiring.

NOTE:

When using a

4 - 20mA process input, the input impedance is 249Ω.

4 - 20mA Process Input

Model # 942A - 2 _ _ _ - _ 000

942A - 3 _ _ _ - _ 000

A jumper must be	1		IDC		+
installed between	2
Terminals #2 and 3.	3				-

10

WATLOW Series 942 User's Manual

Install and Wire, Chapter 2

Output 1 Wiring

Solid State Relay With Contact Suppression, Output 1

Model # 942A - _ B _ _ - _ 000

Solid State Relay, Form A, 0.5 Amp

		External
17	N.O.	Load	L2
18	COM.		L1

Fuse

Solid State Relay With Contact Suppression

Watlow's solid state relay changes state at zero volts, which is "zero-cross switching." They are also optically isolated, which means the output circuitry is energized by infrared light striking a photosensitive device. This results in a virtual absence of electrically generated noise, and provides electrical isolation between the input and output. For use in switching mercury relays or small AC loads. Off state impedance is 20KΩ minimum.

Figure 12 -

Solid State Relay

With Contact

Suppression,

Output 1 Wiring.

NOTE:

This output is supplied with an arc suppression snubber across the output terminals. High impedance loads may remain energized even though the output device is turned OFF.

Switched DC Output (Open Collector), Output 1

Model # 942A - _ C _ _ - _ 000

Switched DC, Open Collector, Non-Isolated

Logic	16	-	External
Switch	17	+	Load

Switched DC

Watlow's solid state switch is a low current DC output (open collector) used to switch an external power switching device such as an SSR or an electromechanical relay. The input specifications of the power switching device must match those listed for the SS switch output. The power switching device must provide isolation between the SS switch output and load power since the SS switch output is a non-isolated output. Minimum load resistance is 500Ω. Available current is 22mA maximum. Typical voltage drop across a 1KΩ load is 12 to 19 volts.

Figure 13 -

Switched DC

(Open Collector),

Output 1 Wiring.

Install and Wire, Chapter 2

WATLOW Series 942 User's Manual

11

Output 1 Wiring

Figure 14 -

6 Amp Mechanical

Relay, Output 1

Wiring.

NOTE:

This output is supplied with an arc suppression snubber across the output terminals. High impedance loads may remain energized even though the output device is turned OFF.

Mechanical Relay, 6 Amp, Form C, Output 1

Model # 942A - _ D _ _ - _ 000

Mechanical Relay, Form C, 6 Amp

16	COM.			Fuse
							L1
17	N.O.						L2
18	N.C.		External
			Load

Mechanical Relay

The electromechanical relay is an electrical and mechanical device with moving parts. When power is applied to the relay solenoid, contact closure is created through movement of the "common" contact of the relay.

Off state impedance is 20KΩ minimum.

Process, 0 - 10VDC, Output 1

Model # 942A - _ E _ _ - _ 000

Figure 15 -

Process, 0 - 10VDC, Process, 0-10VDC, Non-Isolated

Output 1 Wiring.

-	16	-	External
+		+
	17		Load

Process Output

Proportional value determined by the control to balance the sensor input and set point. This value will fall between 0 - 10VDC depending on the thermal characteristics of the system.

Load impedance is 10KΩ minimum.

12

WATLOW Series 942 User's Manual

Install and Wire, Chapter 2

Output 1 Wiring

Process, 4 - 20mA, Output 1

Model # 942A - _ F _ _ - _ 000

Figure 16 -

Process, 4 - 20mA,

Output 1 Wiring.

Process, 4-20 mA, Non-Isolated

+	17	+	External
IDC	18
		-	Load
-

Process Output

Proportional value determined by the control to balance the sensor input and set point. This value will fall between 4 - 20mA depending on the thermal characteristics of the system.

Load impedance is 600Ω maximum.

Process, 0 - 20mA, Output 1

Model # 942A - _ G _ _ - _ 000

Figure 17 -

Process, 0 - 20mA,

Output 1 Wiring.

Process, 0-20 mA, Non-Isolated

-	16	-	External
IDC	17
		+	Load
+

Process Output

Proportional value determined by the control to balance the sensor input and set point. This value will fall between 0 - 20mA depending on the thermal characteristics of the system.

Load impedance is 600Ω maximum.

Install and Wire, Chapter 2

WATLOW Series 942 User's Manual 13

Output 1 Wiring

Process, 0 - 5VDC, Output 1

Model # 942A - _ H _ _ - _ 000

Figure 18 -

Process, 0 - 5VDC,

Output 1 Wiring.

Process, 0-5VDC, Non-Isolated

+	17	+	External
-	18
		-	Load

Process Output

Proportional value determined by the control to balance the sensor input and set point. This value will fall between 0 - 5VDC depending on the thermal characteristics of the system.

Load impedance is 10KΩ minimum.

Solid State Relay Without Contact Suppression, Output 1

Model # 942A - _ K _ _ - _ 000

Figure 19 -

Solid State Relay

Without Contact

Suppression, Output

1 Wiring.

Solid State Relay, Form A, 0.5 Amp

		External
17	N.O.	Load	L2
18	COM.		L1

Fuse

Solid State Relay Without Contact Suppression

Watlow's solid state relay changes state at zero volts, which is "zero-cross switching." They are also optically isolated, which means the output circuitry is energized by infrared light striking a photosensitive device. This results in a virtual absence of electrically generated noise, plus output to input electrical isolation. Off state impedance is nearly infinite and should be used to switch high impedance non-inductive loads.

14

WATLOW Series 942 User's Manual

Install and Wire, Chapter 2

Output 2 Wiring

Solid State Relay With Contact Suppression, Output 2

Model # 942A - _ _ B _ - _ 000

Solid State Relay, Form A, 0.5 Amp

Fuse

14

N.O.

L1L2

COM.

L1

15

External

L2

Load

Solid State Relay With Contact Suppression

Watlow's solid state relay changes state at zero volts, which is "zero-cross switching." They are also optically isolated, which means the output circuitry is energized by infrared light striking a photosensitive device. This results in a virtual absence of electrically generated noise, and provides electrical isolation between the input and output. For use in switching mercury relays or small AC loads. Off state impedance is 20KΩ minimum.

Figure 20 -

Solid State Relay

With Contact

Suppression,

Output 2 Wiring.

NOTE:

This output is supplied with an arc suppression snubber across the output terminals. High impedance loads may remain energized even though the output device is turned OFF.

Switched DC Output (Open Collector), Output 2

Model # 942A - _ _ C _ - _ 000

Switched DC, Open Collector, Non-Isolated								Figure 21 -
		+	14		+			Switched DC Output
	Logic						External	(Open Collector),
		-		15	-
	Switch						Load	Output 2 Wiring.

Switched DC

Watlow's solid state switch is a low current DC output (open collector) used to switch an external power switching device such as a SSR or an electromechanical relay. The input specifications of the power switching device must match those listed for the S.S. switch output. The power switching device must provide isolation between the S.S. switch output and load power since the S.S. switch output is a non-isolated output. Minimum load resistance is 500Ω. Available current is 9mA minimum and 22mA maximum.

Install and Wire, Chapter 2

WATLOW Series 942 User's Manual

15

Output 2 Wiring

Mechanical Relay, 6 Amp, Form A, Output 2

Model # 942A - _ _ D _ - _ 000

Figure 22 -

6 Amp Mechanical

Relay, Output 2

Mechanical Relay, Form A, 6 Amp

External

Wiring.

14

N.O.

Load

L1

L2

15

COM.

L1

L2

Fuse

NOTE:

This output is supplied with an arc suppression snubber across the output terminals. High impedance loads may remain energized even though the output device is turned OFF.

Mechanical Relay

The electromechanical relay is an electrical and mechanical device with moving parts. When power is applied to the relay solenoid, contact closure is created through movement of the "common" contact of the relay. Off state impedance is 20KΩ minimum.

Solid State Relay Without Contact Suppression, Output 2

Model # 942A - _ _ K _ - _ 000

Figure 23 -

Solid State Relay, Form A, 0.5 Amp

Fuse

Solid State Relay

14 N.O.

L12

Without Contact

15 COM.

L1

Suppression,

External

L2

Output 2 Wiring.

Load

Solid State Relay Without Contact Suppression

Watlow's solid state relays change state at zero volts, which is "zero-cross switching." They are also optically isolated, which means the output circuitry is energized by infrared light striking a photosensitive device. This results in virtual absence of electrically generated noise, while providing output to input electrical isolation. Off state impedance is nearly infinite and should be used to switch high impedance non-inductive loads.

16

WATLOW Series 942 User's Manual

Install and Wire, Chapter 2

Auxiliary Wiring

For more information on alarms, alarm jumper selection and events, see Chapter 6.

Mechanical Relay

The electromechanical relay is an electrical and mechanical device with moving parts. When power is applied to the relay solenoid, contact closure is created through movement of the "common" contact of the relay. Off state impedance is 20KΩ minimum.

Mechanical Relay, 6 Amp, Single Form A or B, Auxiliary Output

Model # 942A- _ _ _ 1 - _ 000

Mechanical Relay, Form A or B, 6 Amp

26

Output #3			L1
	27	Load	L2

Mechanical Relay, 6 Amp, Dual Form A or B, Auxiliary Output

Model # 942A- _ _ _ 2 - _ 000

Mechanical Relay, Form A or B, 6 Amp

24

Fuse

Output #4

L1

25

Load

L2

26

Fuse

Output #3

L1

27

Load

L2

Figure 24 -

Auxiliary Option 1

Wiring.

NOTE:

This output is supplied with an arc suppression snubber across the output terminals. High impedance loads may remain energized even though the output device is turned OFF.

Figure 25 -

Auxiliary Option 2

Wiring.

Install and Wire, Chapter 2

WATLOW Series 942 User's Manual 17

Auxiliary Wiring

Mechanical Relay

The electromechanical relay is an electrical and mechanical device with moving parts. When power is applied to the relay solenoid, contact closure is created through movement of the "common" contact of the relay.

Mechanical Relay, 6 Amp, Form A or B/0 - 5VDC Retransmit

Model # 942A- _ _ _ 3 - _ 000

Figure 26 -

Auxiliary Option 3

Wiring.

NOTE:

This output is supplied with an arc suppression snubber across the output terminals. High impedance loads may remain energized even though the output device is turned OFF.

Process, 0-5VDC, Non-Isolated

Mechanical Relay, Form A or B, 6 Amp

-

External

+

24

Load

Output #4

-

25

Fuse

Output #3

+

26

L1

27

Load

L2

Load impedance 10KΩ mimimum.

Mechanical Relay, 6 Amp, Form A or B/4 - 20mA Retransmit

Model # 942A- _ _ _ 4 - _ 000

Process, 4-20 mA, Non-Isolated

Figure 27 -

Mechanical Relay, Form A or B, 6 Amp

+

Auxiliary Option 4

External

-

Wiring.

-

24

Load

IDC

25

Fuse

+

26

L1

27

Load

L2

Load impedance 600Ω maximum.

18

WATLOW Series 942 User's Manual

Install and Wire, Chapter 2

Auxiliary Wiring

Retransmit Output

When using a retransmit output such as 0 - 5VDC or 4 - 20mA, the rL and rH settings scale the range of the retransmit output.

An example of this is: By setting rL = 0, rH = 1000 and Ot4 = PrOC a process value of 500 will result in a retransmitted signal of 2.5VDC or 12mA.

0 - 5VDC Retransmit, Auxiliary Output

Model # 942A- _ _ _ 5 - _ 000

Figure 28 -

Auxiliary Option 5

Wiring.

Process, 0-5VDC non-isolated

-	24	-	External
	25	+
+			Load

Load impedance 10KΩ mimimum.

4 - 20mA Retransmit, Auxiliary Output

Model # 942A- _ _ _ 6 - _ 000

	Figure 29 -
Process, 4-20 mA, Non-Isolated	Auxiliary Option 6
	Wiring.

	-				24	+
									External
IDC				25		-
									Load
		+
Load impedance 600Ω maximum

Install and Wire, Chapter 2

WATLOW Series 942 User's Manual

19