Process Signal Multiplexer - 8 to 1 User Manual
Contents
1. o jad jr IC IC IO ICO O O _ _ O O O CO O O O a O _ _ _ 2 Page Using eight multiplexers to expand an eight analogue Using multiple multiplexers with three digital outputs for input system to 64 analogue inputs by using 11 digital the address lines and a digital output to select each outputs for multiplexer selection and input addressing individual multiplexer To Analogue Input 1 To Analogue Input 2 To Analogue Input 8 3lPage edanntech PROCESS INSTRUMENTATION 2013 Circuit Configurations The general circuit diagram for each input is shown below However for each input type some of the protection components need to be removed as they can affect the measurement 100 Q L L vy A A 100nF ai i Transorb 36V Bi Polar Out Transorb from other inputs Resistance Input Type Thermocouple pT100 pT1000 Voltage PL MUX8 1 TC C PL MUX8 1 R C PL MUX8 1 I C PL MUX8 1 V C Process Signal Mux 8 Process Signal Mux 8 Process Signal Mux 8 Process Signal Mux 8 to 1 TC Input 24VDC to 1 R Input 24VDC to 1 Input 24VDC to 1 V Input 24VDC 10 Q seri i Left in No eff S E Left in No eff 0 Q series resistor eft in No effect add measurement Levine Lae ecc e dy a es for signal with high Z filtering noise transmitter input R32 cae R39 Ue ere transmitter input limiting Good for filtering2. out palace a OR or 9 Good for filtering SOl 100 Q termination resistor for current Left in Provides N P loop continuity Left in No effect Leftin No effect realistic loop Bare Pan iC when the input is on TC not on resistance not resistance when o Aee A NOT selected i e selected selected the input is not R16 through E relay is in the OFF selected R23 out state Transorbs for spike protection which can occur in current loop circuits Reduces voltage surges due to switching in constant current circuits Extends relay contact life 100 nF capacitors for reduction of switching noise and signal filtering see note below It may be desirable to remove C2 through to C9 100nF capacitors after the relay on the right of the relay in the circuit diagram above to improve response time when switching channels and also C18 through to C25 100nF capacitors before the relay on the left of the relay in the circuit diagram above to improve individual channel step responses this will depend upon the application 4 Page danntech PROCESS INSTRUMENTATION 2013 Component Layout OUT Si S2 S3 S4 S5 S6 S7 SB OU AO Al A2 EN EN 24U danntech 2000 DT295 1 C SI DE R 2 N uy C18 C25 IN2 IN1 IN3 IN4 IN5 IN6 IN7 IN8 Signal Switching Effects There are some things to keep in mind when switching process signals either as inputs from sensors or output
3. ve or OV Signal Input 5 ve or OV N7 Signal Input 7 ve or OV Signal Input 8 ve or OV Signal Input 8 ve Output and Controls Terminal Description Maring O 0ta O Selected Signal Output ve or OV Description S1 S2 S3 S4 S5 S6 S7 S8 i connected to 24V AO A1 A2 EN N Decoded input 1 OS S2 OSS O S4 55 o S6 O S7 ov corner or aeons inais selection for Input 8 AO OM awn ENRBLE o input 2 Mo ENABLE o m when high all relays are disabled All off can be to 24V ENABLE controlled by E When low all relays are disabled Must be S1 S8 high can be via J1 for any inputs to be All off can be selected controlled by Power supply input 24 VDC S1 S8 Power supply OV connected to OV X don t care Note that the enable inputs only apply to the decoded inputs AO to A2 the S1 to S8 inputs are not affected by the ENABLE control inputs 6 Page edanntech PROCESS INSTRUMENTATION 2013 Specifications Input Selection Individual input selection using eight digital inputs S1 to S8 Multiplexed relay selection using three digital inputs AO A1 and A2 with decoder and enable inputs Selection inputs S1 to S8 have an input impedance of 20 kQ 1 1 mA at 24 V 2 2 mA at 12 V Decoded selection inputs AO to A2 have input impedance of 10 kQ 2 2 mA at 24 V 4 4 mA at 12 V Enable inputs have an input impedance of 10 kQ 2 2 mA at 24 V 4 4 mA at 12 V LED i
4. Filename Process Signal Multiplexer 8 to 1 User Manual docx Date 25 November 2013 Version 1 2 Process Signal Multiplexer 8 to 1 User Manual Description The Process Signal Multiplexer provides a low cost way of selecting one of eight or more analogue signals Typically this could be used to switch multiple sensors into a transmitter or one of many transmitter outputs into a single analogue PLC input High quality signal grade relays rated for a minimum of 15 million operations are used to select the input signals Four versions provide suitable inputs for Thermocouples resistance sensors pT100 pT 1000 4 voltage and current Two input selection options are available either eight digital inputs switching each relay separately or using only three digital inputs with the binary equivalent used to switch the required input so that only three digital inputs are required 100 Q Out S1 S2 s3 S4 100 Q Two enable inputs are provided so for lt flexibility implementing other selection options An example could be controlling two multiplexers with four digital inputs Hv o The digital inputs required are from 16 to 30 VDC and LEDs indicate which input is active Multiple multiplexers can be used 100 Q S6 to switch any number of sensors or IN 4 oF analogue inputs It is best to order the l correct unit for your type of inputs so that 100 i the input adjustments are made for you be
5. fore delivery See the part numbering il si information for details to order the correct device for your application hated The input relay selection can be made ii using either the direct acting S1 through S8 inputs or the decoded AO A1 and A2 inputs with the ENABLE controls IN7 A1 100 Q A0 24V 100 Q J1 zZz uo iri jia iain pe O edi le we ow Enable Enable IN8 LED ih 24V 24V Power included for the current and thermocouple input versions en ov removed for all other versions 1 Page danntech PROCESS INSTRUMENTATION 2013 Applications The drawing below illustrates an application where eight thermocouples or eight pl 100s can be scanned into a single transmitter using a PLC or similar type controller PROCESS SIGNAL MULTIPLEXER ob 4 4 e i j D D ee ee ee ee THERMOCOUPLES _ TEMPERATURE TRANSMITTER 4 5 pas 2 P YDJUUOP 4 20mA DIGITAL INPUTS O SELECT EACH THERMOCOUPLE IN1 IN2 IN3 IN4 INS A ING IN7 ENABLE Hl IN OUT IN10 IN11 IN12 IN13 IN14 IN15 IN16 danntech PROCESS INSTRUMENTATION 2013 Using two multiplexers with four digital outputs to select the inputs AO A1 Ce M C o EnmmE p wwxse ov muts 118 24 V Inputs 9 to 16 z gt lo 0 00 1M2 Ooo olojo O O oO _ o loj lolol lolo
6. ndication of selected input When using the individual input selection inputs S1 to S8 the enable controls cannot be used and J1 must be removed to disable the decoded selection inputs Either input type can be used by connecting to the appropriate terminals J1 must be removed for direct S1 to S8 control Enable Control Inputs The ENABLE input is pulled high by J1 so if J1 is inserted then the decoded selection inputs are enabled The NOT ENABLE input is pulled low internally Inputs Four versions provide suitable input configurations for thermocouples resistance sensors pT 100 01 1000 voltage and current inputs Maximum input voltage 30 V maximum input current 30 mA with 100 termination resistors installed Relays Fully sealed low signal relays gold plated contacts Response time approximately 10 mSecs Contact rating 2 A at 30 VDC 500 mA at 125 VAC Life expectancy more than 15 million operations Isolation greater than 500 VAC Omron Type G5V 2 plug in fitting so they can be replaced if necessary Minimum load 10 uA 10 mV DC LED Indication Green LED indication of power supply and green LED indication of active selected input Isolation Galvanic isolation between unselected inputs gt 500 VAC Power 24 VDC 410 auxiliary power supply at approximately 50 mA Temperature Operating temperature 10 C to 60 C Storage temperature 20 C to 80 C Mechanical Screw terminals to accommodate wire sizes
7. s of transmitters Process signal transmitters react in various ways to a fluctuating switching input signal For example in the case of a thermocouple input temperature transmitter the switching of the input signal may be detected as a brief open sensor event by a transmitter The transmitter may then see this as a TC burnout and output a fault level signal for a while typically 2 or 22 mA until a stable input is returned So in this case one would need to either disable this feature in the transmitter or allow enough time for the transmitter output signal to settle In the case of selecting various loop currents which are outputs of process signal transmitters when the output circuit of such a transmitter goes open circuit however briefly the loop voltage may spike to try and maintain the loop current This effect will depend upon the reaction time of the output circuit of the transmitter and can be reduced or limited by the use of transorbs and basic filtering Again allowing enough settling time between signal switching is important The termination resistors used for the current input options try to reduce this effect so that the transmitter output sees a fairly constant load resistance except of course during the brief switching period Another application we have had experience with is where a multiplexer is used to monitor the individual cell voltage in a battery Since each input is at a different potential and the bat
8. tery is capable of providing large currents if there is any switching overlap whatsoever there could be voltage spikes at the output and any current flowing can damage the relay contacts If the relay contacts are damaged incorrect measurements can result or complete input failure To avoid this one should allow some inter switching time this is where none of the relays are selected This is fairly easy to do when using the individual selection inputs S1 through S8 but more difficult when using the decoded inputs AO A1 and A2 In the case of the decoded inputs being used we recommend using the ENABLE input to provide the inter switching delay Basically the procedure could be ENABLE low set up the address of the input required wait a short while 0 5 s ENABLE high wait a short while 0 5 s for measurement to settle read the analogue input then repeat S5SIPage edanntech PROCESS INSTRUMENTATION 2013 It may be desirable to remove C2 through to C9 100nF capacitors after the relay on the right of the relay in the circuit diagram above to improve response time when switching channels and also C18 through to C25 100nF capacitors before the relay on the left of the relay in the circuit diagram above to improve individual channel step responses this will depend upon the application Connections Signal Inputs Terminal Marking Signal Input 1 ve or OV Signal Input 2 ve or OV Signal Input 3 ve or OV Signal Input 4
9. up to 1 5 mm Module dimensions 103 x 126 x 50 mm width x length top to bottom x height off DIN rail Module mass 200 g Package dimensions 260 x 170 x 80 mm length x width x height Package mass 400 g 7 Page edanntech PROCESS INSTRUMENTATION 2013 co 53 s3 a Ae pu po al 82 ED EN tes ACC C Ye Saws ORT FLAUTA a s A A TES ye ie ae ee nt A A m a t ma askia E errs M HIN T Na N INS Part Numbering PL MUXn m tt p n Number of Inputs 8 Eight m Style O Open DIN Rail Mounting tt Input Type TC Thermocouple R resistance or pT100 pT1000 V voltage current p Power Supply C 24 VDC D 12 VDC Part Numbering PL MUX8 1 TC C PL MUX8 1 R C PL MUX8 1 I C PL MUX8 1 V C Process Signal Mux 8 to 1 TC Input 24VDC Process Signal Mux 8 to 1 R Input 24VDC Process Signal Mux 8 to 1 Input 24VDC Process Signal Mux 8 to 1 V Input 24VDC danntech PROCESS INSTRUMENTATION 2013 Process Signal Mux 8 to 1 tt Input 24VDC danntech cc Reg No CK1986 15338 23 Tel 27 0 11 792 1239 Fax 27 0 11 792 4687 P O Box 1023 Fontainebleau 2032 Republic of South Africa www danntech com danntech itd Co No 6510211 Tel 44 0 75 9069 1824 15 College Close Hamble le Rice Southampton Hampshire S031 4QU United Kingdom www uk danntech com 8 Page
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