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DRA-RTM-8
AN ALO G MULTIPLEXER
Contents
1. GENERAL DESCRIPTION
2. MOUNTING INSTRUCTIONS
3. REPLACING FUSES
4. ASSEMBLY
5. CURRENT INPUTS
6. CONNECTING TRANSMITTERS TO THE MULTIPLEXER
7. CONNECTING Pt-100 TO THE MULTIPLEXER
8. CONNECTING THE MULTIPLEXER TO A PLC
9. CONTROL
9.1 Enable
9.2 Address
9.3 Address Polarity
9.4 Control Tables
10. CALIBRATION
10.1 Calibration Procedure
10.2 Calibration Tables
10.2.1 "ZERO" - Coarse Calibration Tables
10.2.2 "SPAN" - Coarse Calibration Tables
11. MULTIDROP CONFIGURATION
12. SPECIFICATIONS
1
1. GENERAL DESCRIPTION
The DRA-RTM-8 is a multiplexer for 16 analog inputs - eight of which, marked
1-8, are direct inputs for Pt-100 sensors, while the remaining (9-16), are for 4-
20mA current loops.
The DRA-RTM-8 output format is a 4-20mA current loop, with a 28mA limitation.
Each Pt-100 input has its own signal conditioner, allowing each input to be
calibrated separately. Each signal conditioner includes six DIP switches for coarse
calibration and two potentiometers for fine tuning.
2. MOUNTING INSTRUCTIONS
The DRA-RTM-8 is designed for standard DIN rail mounting.
Place the unit on the upper part of the mounting rail with the fastening tab facing
down. Using a suitable flat screwdriver loosen the tab slightly and attach the unit
to the rail. Once the tab is loosened, ensure that the unit is fastened securely in
place.
3. REPLACING FUSES
To replace a blown fuse, disassemble the unit as follows:
a. Take off both terminal strips by removing the four screws at the edges.
Note: This does not require disconnecting the cables connected to the strips.
b. Remove the front panel using a suitable flat screwdriver. Press down gently on
the plastic springloaded tabs located in the slots on either side of the unit.
c. Disconnect the flat connectors which connects the front panel printed circuit.
d. Replace the blown fuse.
WARNING: Never install a fuse rated more than 800mA
4. ASSEMBLY
The DRA-RTM-8 unit includes two printed circuit cards designated as P.N 7020
and P.N 7021. The two printed circuit cards should occupy the slots in the
enclosure according to fig 1.
2
Insert the two printed cards into their slots.
Connect the flat cable between them.
Connect the front panel flat cables. The
panel must be inserted into the grooves on
both sides of the case while pressing down
until a distinct "click" is heard. Assembly is
completed by laying the terminal strips in
place.
Figure 1.
Note: The terminal strips are polarized and must not be placed backwards.
5. CURRENT INPUTS
The eight 4-20mA current inputs are marked as channels 9-16. These inputs are
for current only. The "COM" input is the return for all the current channels. It is
possible to connect any current source, as long as a closed loop is maintained.
WARNING: Voltage sources should not be connected to the current
inputs,as permanent damage might occur.
6. CONNECTING TRANSMITTERS TO THE MULTIPLEXER
6.1 TWO WIRE TRANSMITTER
A Two-Wire transmitter is connected so that its
positive terminal is connected to the positive
terminal of the power supply, and its negative
terminal is connected to the "I" terminal.
(see fig 2)
Figure 2.
6.2 FOUR WIRE TRANSMITTER
A Four-Wire transmitter is connected so that its
positive terminal is connected to the "I" terminal,
and its negative terminal is connected to the
"COM" terminal. (see fig 3)
3
Figure 3.
7. CONNECTING Pt-100 TO THE MULTIPLEXER
The Pt-100 probe should be connected according to fig 4. The
three wires connecting the probe should be identical.
The distance of the probe can be up to 200 meters.
A shielded cable is recommended.
The shield should be grounded at one point. When possible,
connect the ground at the multiplexer's end.
Figure 4.
8. CONNECTING THE DRA-RTM-8 TO A PLC
The multiplexer output should be connected to 4-20mA input of the PLC analog
module (see fig 5).
The DRA-RTM-8 multiplexer generates the output current, therefore the PLC analog
module should be configured for four wire transmitter connection.
WARNING: NEVER apply 24Vdc to the DRA-RTM-8's +Io terminal
as in two-wire connection, and make sure that the PLC's
analog module is configured as a passive input.
9. CONTROL
The DRA-RTM-8 unit is controlled via four
address lines and one E (Enable) line.
The control terminals (Address and
Enable), were designed to receive control
signals from TTL levels up to 60V so that
almost any PLC's DC output module can
be used. (see fig 5)
Figure 5.
9.1 ENABLE
The unit is enabled when a logical "1" (5V < E < 60V) is connected to the E
Terminal. In a disabled state, the DRA-RTM-8 outputs no current and reflects a
Hi-Z state. This feature allows the connection of several DRA-RTM-8 units by tying
their outputs and control in parallel and addressing them by controlling the
individual Enable terminals.
4
9.2 ADDRESS
The required channel is selected by
four address lines.
The operating voltages are:
Logical "1" 5V < Vi < 60V
Logical "0" 0V < Vi< 0.5V
Figure 6.
9.3 ADDRESS POLARITY (see fig 6)
Address polarity is controlled by three internal pins and a jumper over two of them,
located on PN 7021 printed circuit board, accessible behind the Enable terminal.
The unit is supplied with the jumper set for "true high" control logic, i.e. "0000"
selects channel #1, and "1111" selects channel #16.
Moving the jumper to the second alternative, reverses the logic.
Note: If the address contros voltages are generated from different power
supplies, then its negative terminal should be connected to the
DRA-TM-8's "COM" terminal.
9.4 CONTROL TABLES
9.4.1 "TRUE LOW" SETTING
ADDRESS BUS
A3 A2 A1 A0
ADDRESS BUS
A3 A2 A1 A0
OUTPUT
CHANNEL
OUTPUT
CHANNEL
E
E
0
0
0
0
0
0
0
0
x
0
0
0
0
1
1
1
1
x
0
0
1
1
0
0
1
1
x
0
1
0
1
0
1
0
1
x
1
1
1
1
1
1
1
1
0
16
1
1
1
1
1
1
1
1
x
0
0
0
0
1
1
1
1
x
0
0
1
1
0
0
1
1
x
0
1
0
1
0
1
0
1
x
1
1
1
1
1
1
1
1
0
8
15
7
14
6
13
5
12
11
4
3
10
2
9
1
NO OUTPUT
NO OUTPUT
5
9.4.2 "TRUE HIGH" SETTING
ADDRESS BUS
A3 A2 A1 A0
OUTPUT
CHANNEL
ADDRESS BUS
A3 A2 A1 A0
OUTPUT
CHANNEL
E/ T
E/ T
0
0
0
0
0
0
0
0
x
0
0
0
0
1
1
1
1
x
0
0
1
1
0
0
1
1
x
0
1
0
1
0
1
0
1
x
1
1
1
1
1
1
1
1
0
1
1
1
1
1
1
1
1
1
x
0
0
0
0
1
1
1
1
x
0
0
1
1
0
0
1
1
x
0
1
0
1
0
1
0
1
x
1
1
1
1
1
1
1
1
0
9
2
10
3
11
4
12
5
6
13
14
7
15
16
8
TEST MODE
TEST MODE
Note: The unit includes three internal potentiometers. These potentiometers
are carefully adjusted and sealed in the factory. It is not recommended
to alter these calibration potentiometers.
10. CALIBRATION
To calibrate the DRA-RTM-8, the limits must be defined.
Tmin is the temperature at which the output current is 4mA.
Tmax is the temperature at which the output current is 20mA.
Tspan is the difference between Tmax and Tmin.
10.1 CALIBRATION PROCEDURE
a. Remove the terminal strips to get access to the coarse calibration switches.
b. Set the channels DIP switches to the desired calibration ranges according to the
calibration tables.
c. Re-install the terminals strips. The terminal strips are polarized and should be
returned to their original position.
d. Connect a Pt-100 calibrator* set for Tmin to the proper input terminals.
e. Apply the proper channel selection code by connecting those which according
the table should be "1" to the +PWR terminal.
f. Start calibrating by adjusting the proper "Z" potentiometer to obtain an output
current of 4.000mA.
g. Set the calibrator for Tmax and adjust the "S" potentiometer to obtain an output
current of 20.000mA.
h. Repeat this procedure until satisfactory results are obtained.
6
i. Change the address to the next channel to be calibrated.
j. Repeat steps b to h
* The calibrator is set according to DIN 43760 Pt-100 table (a = 0.00385)
10.2 CALIBRATION TABLES
Note: Logic state of "0" is when the DIP switch lever is down.
10.2.1 "ZERO" - COARSE CALIBRATION TABLES
CHANNELS 1-4
CHANNELS 5-8
O
ZERO TEMP C
SW6 SW5 SW4
SW1 SW2
SW3
1
1
1
1
0
0
1
1
0
0
-50.....10
8.....75
1
1
1
0
0
1
1
0
0
1
1
1
1
0
0
0
0
1
0
1
0
1
0
1
0
0
1
0
1
0
1
0
74...140
1
1
139...206
205...272
270...338
336...404
401...470
0
0
0
0
10.2.2 "SPAN" - COARSE CALIBRATION TABLES
CHANNELS 1-4
CHANNELS 5-8
O
SPAN C
SW1
1
SW6
1
SW2 SW3
SW4
1
SW5
1
50.....76
1
0
1
1
0
0
1
1
1
0
1
0
1
1
0
0
0
1
1
0
0
65...115
1
0
0
1
0
1
110...180
135...225
215...440
400...800
0
0
0
0
0
7
11. MULTIDROP CONFIGURATION
In the disabled state (E=0), the multiplexer outputs no current and exhibits a high
Z state. This mode allows the connection of several DRA-RTM-8 units to one PLC's
analog input, by tying their output terminals and the address lines in parallel, and
applying individual Enable lines to select the desired multiplexer by disabling all
but one (see fig 7).
ANALOG
ANALOG
+
-
PLC
ANALOG
INPUT
MODULE
ENABL
E
1
2
ENABL
E
MSB
DISCRETE
OUTPUT
MODULE
LSB
Figure 7.
12. SPECIFICATIONS
8, Pt-100 Channels a=0.00385
ANALOG INPUTS:
8, 0/ 4-20mA Channels
RTD INPUT:
50 to +200 oC
Zero adjustability:
Span adjustability:
Lead Compensation Error:
Max Lead Resistance:
Pt-100 linearization:
50 to 750 oC
0.025 oC for 10W lead resistance
120
W
two ways
0.1% of span max.
CURRENT INPUT
30 mA
Max Input Current:
Yes
Reverse Polarity Protection:
Output Accuracy (Refer to Current Input):
0.1% of span max.
4 Address
1 Enable input
CONTROL INPUTS:
True High or True Low (User selectable)
Low: "0" < 0.5V High: 5 < "1" < 60V
Logic:
Logic Levels:
4-20mA, Current Loop
OUTPUT:
< 20mSec (into a resistive load)
1 Yellow LED, Power-On indicator
8 Red LEDs, current activity indicators
SWITCHING TIME:
INDICATORS:
24 10% Vdc (regulated)
120 mA 10mA
SUPPLY VOLTAGE:
SUPPLY CURRENT CONSUMPTION:
FUSE:
150 mA, Fast Blow (5x20mm)
0.01% of span/ 1 oC
TEMPERATURE STABILITY:
OPERATING TEMPERATURE:
STORAGE TEMPERATURE:
HUMIDITY:
0 to 60 oC (32 to 140 oF)
-25 to +85 oC (-13 to 185 oF)
5 to 95% Relative humidity, non-condensing
Plastic Polycarbonate
According to IP50 DIN 40050
According to IP20 DIN 40050
HOUSING:
Box:
Terminal:
0.9 Kg. (2.0 lb.)
WEIGHT:
73Hx200Wx121mmD (2.88"x7.88"x4.76")
DIMENSIONS:
8
WARRANTY/DIS CLAIMER
OMEGA ENGINEERING, INC. w a rra n ts th is u n it to b e fre e o f d e fe cts in m a te ria ls a n d workm anship
fo r a p e rio d o f 1 3 m o n t h s fro m d a te o f p u rch a s e . OMEGA Wa rra n ty a d d s a n a d d itio n a l o n e (1) m o n th
g ra ce p e rio d to th e n o rm a l o n e (1 ) y e a r p r o d u c t w a r r a n t y to cover handling and shipping tim e. This
ensures that OMEGA’s custom ers receive m axim um coverage on each product. If the unit should m alfunction,
it m ust be returned to the factory for evaluation. OMEGA’s Custom er Service Departm ent will issue an Authorized
Return (AR) num ber im m ediately upon phone or written request. Upon exam ination by OMEGA, if the unit is
found to be defective it will be repaired or replaced at no charge. OMEGA’s WARRANTY does not apply to defects
resulting from any action of the purchaser, including but not lim ited to m ishandling, im proper interfacing,
operation outside of design lim its, im proper repair, or unauthorized m odification. This WARRANTY is VOID if
the unit shows evidence of having been tam pered with or shows evidence of being dam aged as a result
of excessive corrosion; or current, heat, m oisture or vibration; im proper specification; m isapplication; m isuse
or other operating conditions outside of OMEGA’s control. Components which wear are not warranted, including
but not lim ited to contact points, fuses, and triacs.
OMEGA is p le a s e d t o o ffe r s u g g e s t io n s o n t h e u s e o f it s va rio u s p ro d u c t s . Ho w e ve r,
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o n ly t h a t t h e p a rt s m a n u fa c t u re d b y it w ill b e a s s p e c ifie d a n d fre e o f d e fe c t s .
OMEGA MAKES NO OTHER WARRANTIES OR REP RES ENTATIONS OF ANY KIND
WHATS O EVER, EX P RES S ED O R IM P LIED , EX C EP T THAT O F TITLE, A N D A LL
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P r o d u c t (s ) in s u c h
a
m a n n e r.
RETURN REQUES TS / INQUIRIES
Direct all warranty and repair requests/inquiries to the OMEGA Custom er Service Departm ent.
BEFORE RETURNING ANY PRODUCT(S) TO OMEGA, PURCHASER MUST OBTAIN AN AUTHORIZED
RETURN (AR) NUMBER FROM OMEGA’S CUSTOMER SERVICE DEPARTMENT (IN ORDER TO AVOID
PROCESSING DELAYS). The assigned AR num ber should then be m arked on the outside of the return
package and on any correspondence.
The purchaser is responsible for shipping charges, freight, insurance and proper packaging to prevent
breakage in transit.
FOR WARRANTY RETURNS, please have the
following inform ation available BEFORE contacting
OMEGA:
FOR NON-WARRANTY REPAIRS, consult
OMEGA for current repair charges. Have the
following inform ation available BEFORE
contacting OMEGA:
1. P.O. num ber under which the product was
PURCHASED,
1. P.O. num ber to cover the COST
of the repair,
2. Model and serial num ber of the product under
warranty, and
2. Model and serial num ber of product, and
3. Repair instructions and/or specific
problem s relative to the product.
3. Repair instructions and/or specific problem s
relative to the product.
OMEGA’s policy is to m ake running changes, not m odel changes, whenever an im provem ent is possible.
This affords our custom ers the latest in technology and engineering.
OMEGA is a registered tradem ark of OMEGA ENGINEERING, INC.
©
Copyright 1996 OMEGA ENGINEERING, INC. All rights reserved. This docum ent m ay not be copied,
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W h e re Do I Fin d Eve r y th in g I N e e d fo r
Pro ce ss Me a su re m e n t a n d Co n tro l?
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