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22

Check that the parameters programmed in the instrument’s 

Serial Data Communication Page

 

are compatible with those of the

computer terminal or host computer – see Section 7.

If communication is still not possible or is erratic, check that the computer terminal, or host computer, interface has pull-up ant
pull-down resistors connected as shown in Figs. 11.1 and 11.2.

Note. 

If no reply is received from the instrument within 160ms, retransmit the command. If after five command re-entries

a satisfactory reply has not been received, the communication link has been broken and must be re-checked.

+5V

0V

Pull-up
Resistor

Pull-down
Resistor

Pull-down
Resistor

Computer Terminal or Host Computer

Rx+

Rx–

Tx+

Tx–

'A'

'A'

'B'

'B'

1

2

3

4

5

6

Tx+

Rx+

Tx–

Rx–

Fig. 11.2 Pull-up and Pull-down Resistors (3-wire only)

…11

OPERATION

Summary of Contents for 8241

Page 1: ...Operating Instructions MODBUS Communication Supplement 8240 Series Analyzers OUT OF SERVICE ALARM 1 CAL ALARM 2 HOLD OUT OF SAMPLE Phosphate EIL 8242 ...

Page 2: ...us program of innovative design and development to incorporate the latest technology The NAMAS Calibration Laboratory No 0255 is just one of the ten flow calibration plants operated by the Company and is indicative of our dedication to quality and accuracy BS EN ISO 9001 Cert No Q5907 EN 29001 ISO 9001 Lenno Italy Cert No 9 90A Use of Instructions Warning An instruction that draws attention to the...

Page 3: ... Single Coil 9 8 3 1 Force Single Coil Query 9 8 3 2 Force Single Coil Response 9 8 4 Preset Single Register 10 8 4 1 Preset Single Register Query 10 8 4 2 Preset Single Register Response 10 8 5 Loopback Test 10 8 5 1 Loopback Test Query 10 8 5 2 Loopback Test Response 10 8 6 Preset Multiple Registers 11 8 6 1 Preset Multiple Registers Query 11 8 6 2 Preset Multiple Registers Response 11 9 EXCEPTI...

Page 4: ...preted and acted upon To achieve this second condition MODBUS Protocol is utilized on the 8240 Monitor using the Remote Terminal Unit RTU mode only Two methods of message error checking are used Parity checking is used if selected to detect transmission errors in individual characters Parity is used for simple error checking The parity bit is a one bit code which is transmitted in addition to the ...

Page 5: ...tion does not occur This is often implemented by the use of the RTS signal to control the transmitter enable Consult the adaptor card manufacturer to determine suitability Caution Install the pull up pull down resistors on either the RX or TX lines The resistors must not be connected on both pairs of lines All connections apart from those for serial data communication are made as shown in Figs 2 3...

Page 6: ... Instruction Manual 3 2 1 6 5 4 Output Board Output Board 1 Tx 2 Rx 3 Common 0V 4 Tx 5 Rx 6 No connection A Five wire Connections B Three wire Connections 3 wire 5 wire IC32 IC31 IC33 IC34 C Three and Five wire Links 6 7 1 12 1 Tx Rx 2 Not Connected 3 Common 0V 4 Tx Rx 5 Not Connected 6 Not Connected 6 7 1 12 3 2 1 6 5 4 ...

Page 7: ...1 Termination Resistors Fig 5 1 For long transmission lines termination resistors are required on the last 8240 Monitor in the chain and at the host computer computer terminal Under normal operating conditions the resistors are required at the last 8240 receive inputs only see Fig 4 1 The transmitter s resistors are selected using plug in links see Fig 5 1 Switch off the supply and gain access to ...

Page 8: ...ON PAGE 1 0 Next 5 weekly service DD MM Next yearly service DD MM YY Monitor in service MAINTENANCE AND CALIBRATION PAGE 2 0 Enter security code xxxx SET UP CURRENT OUTPUTS PAGE 4 0 Output range 1 0 to xxx units Calibration hold NO Output range 2 0 to xxx units Calibration hold NO Output type xx to xx mA Test output NO SET UP SERIAL INTERFACE PAGE 3 3 Baud Rate xxxx Parity xxxx ID xx SET UP SERIAL...

Page 9: ...alue before storage in the database 7 MODBUS PROTOCOL 7 1 Introduction to MODBUS Protocol RTU only MODBUS communication is based on a master and a slave arrangement The master sends a message to one slave at a time and waits for a reply The slave cannot accept a new message until the existing message is processed and a reply sent to the master maximum response time 250 milliseconds The slave monit...

Page 10: ...and the number of locations to be interrogated must obtain status data Note The coil offset address is the coil number minus one e g to start at coil 31 the data start value must be set to 30 1EH Example a read coil status request to read 5 coils from slave 01 starting at coil 01 Out of Service is shown below 8 1 2 Read Coil Status Response The data is packed one bit for each coil 1 ON 0 OFF The r...

Page 11: ...0 HEX sets the coil ON and the value zero turns it OFF All other values are illegal and do not affect the coil Note To write to a coil the coil offset address must be used e g to write to coil 10 the coil address 09 09H is transmitted The use of slave address zero broadcast mode forces all attached slaves to modify the desired coil Example a force single coil request to switch ON coil address 10 N...

Page 12: ...s of a holding register Note Function codes 5 6 and 16 are the only messages that are recognized as valid for broadcast Example a preset single register request to write the value 501 to holding register address 50 Output Range 1 in slave 01 is shown below Since all register values for measured variables and alarm set points are ranged to 12 bits for RTU then to calculate the Data Value High and D...

Page 13: ...tion field contains 2 bytes for the designation of the diagnostic code followed by 2 bytes to designate the action to be taken Example 01 08 00 31 04 02 32 C5 Register Offset High Function Address Register Offset Low Error Check Field CRC 16 Data Value High Data Value Low 01 08 00 31 04 02 32 C5 Function Address Error Check Field CRC 16 Data Data Diagnostic Code High Data Data Diagnostic Code Low ...

Page 14: ...rrors it sends a response message to the master consisting of slave address function code error code and error check fields The response is an exception response sighting illegal data address To indicate that the response is a notification of an error the most significant bit of the function code is set to 1 Exception Response Code Exception Response Name Exception Response Definition 01 03 00 FA ...

Page 15: ...f Reagent 1 Monitor Out Of Reagent 008 R Five weekly Service Status 0 Five weekly Service Not Overdue 1 Five weekly Service Overdue 009 R Yearly Service Status 0 Yearly Service Not Overdue 1 Yearly Service Overdue 010 R W Non Vol Memory Mode 0 Disable Write To Non Volatile Memory 1 Enable Write To Non volatile Memory 011 R Calibration Offset Alarm 0 Calibration Offset Inside Of Limits 1 Calibratio...

Page 16: ...ration Month Month 021 R Last Auto Zero Calibration Year Year 022 R Next Secondary Calibration Date Date 023 R Next Secondary Calibration Month Month 024 R Next Secondary Calibration Year Year 025 R Last Secondary Calibration Date Date 026 R Last Secondary Calibration Month Month 027 R Last Secondary Calibration Year Year 028 R W Relay Alarm Hysteresis 0 to 5 029 R W Relay Alarm Failsafe 0 No 1 Ye...

Page 17: ...2000 or 0 to 5000 051 R W Current Output 2 Range Scaled 0 to 2000 or 0 to 5000 052 R W Alarm 1 Relay Setpoint Scaled 0 to 2000 or 0 to 5000 053 R W Alarm 1 Relay On Off Status 0 Off 1 On 054 R W Alarm 1 Relay Action 055 R W Alarm 2 Relay Setpoint Scaled 0 to 2000 or 0 to 5000 056 R W Alarm 2 Relay On Off Status 0 Off 1 On 057 R W Alarm 2 Relay Action 0 Low 1 High 058 R W Alarm Relay Delay 0 to 99 ...

Page 18: ... Stream 6 Decimal Point 0 0 d p 1 1 d p 112 R W Alarm 1 Relay Setpoint Scaled 0 to 2000 or 0 to 5000 113 R W Alarm 1 Relay On Off Status 0 Off 1 On 114 R W Alarm 1 Relay Action 0 Low 1 High 115 R W Alarm 2 Relay Setpoint Scaled 0 to 2000 or 0 to 5000 116 R W Alarm 2 Relay On Off Status 0 Off 1 On 117 R W Alarm 2 Relay Action 0 Low 1 High 118 R W Alarm 3 Relay Setpoint Scaled 0 to 2000 or 0 to 5000...

Page 19: ...emperature Out Of Range 007 R Reagent Status 0 Monitor Not Out Of Reagent 1 Monitor Out Of Reagent 008 R Five weekly Service Status 0 Five weekly Service Not Overdue 1 Five weekly Service Overdue 009 R Yearly Service Status 0 Yearly Service Not Overdue 1 Yearly Service Overdue 010 R W Non Vol Memory Mode 0 Disable Write To Non Volatile Memory 1 Enable Write To Non volatile Memory 011 R Calibration...

Page 20: ...ndary Calibration Date Date 023 R Next Secondary Calibration Month Month 024 R Next Secondary Calibration Year Year 025 R Last Secondary Calibration Date Date 026 R Last Secondary Calibration Month Month 027 R Last Secondary Calibration Year Year 028 R W Relay Alarm Hysteresis 0 to 5 029 R W Relay Alarm Failsafe 0 No 1 Yes 030 R W Current Output Type 0 0 10mA 1 0 20mA 2 4 20mA 031 R W Calibration ...

Page 21: ... 054 R W Alarm 1 Relay Action 055 R W Alarm 2 Relay Setpoint Scaled 0 to 20 0 or 0 to 60 0 056 R W Alarm 2 Relay On Off Status 0 Off 1 On 057 R W Alarm 2 Relay Action 0 Low 1 High 058 R W Alarm Relay Delay 0 to 99 Minutes 059 R W Current Output 1 Hold Status 0 No 1 Yes 060 R W Current Output 2 Hold Status 0 No 1 Yes 081 R W Unit Type 0 P 1 PO4 082 R W Colour Compensation Applied Scaled 0 0 to 60 0...

Page 22: ... p 111 R W Stream 6 Decimal Point 0 1 d p 1 2 d p 112 R W Alarm 1 Relay Setpoint Scaled 0 to 20 0 or 0 to 60 0 113 R W Alarm 1 Relay On Off Status 0 Off 1 On 114 R W Alarm 1 Relay Action 0 Low 1 High 115 R W Alarm 2 Relay Setpoint Scaled 0 to 20 0 or 0 to 60 0 116 R W Alarm 2 Relay On Off Status 0 Off 1 On 117 R W Alarm 2 Relay Action 0 Low 1 High 118 R W Alarm 3 Relay Setpoint Scaled 0 to 20 0 or...

Page 23: ...l instruments Ensure that the serial data connections to the 8240 Monitor have been made correctly with respect to the computer terminal or host computer interface If the above check appears satisfactory test the serial communication by sending an appropriate message from the computer terminal or host computer to a transmitter and observe if it replies thus establishing communication If communicat...

Page 24: ...up ant pull down resistors connected as shown in Figs 11 1 and 11 2 Note If no reply is received from the instrument within 160ms retransmit the command If after five command re entries a satisfactory reply has not been received the communication link has been broken and must be re checked 5V 0V Pull up Resistor Pull down Resistor Pull down Resistor Computer Terminal or Host Computer Rx Rx Tx Tx A...

Page 25: ...n volatile save state is set to Enable any parameter changes made via the serial link are written to the non volatile memory register and retained on power down If the non volatile save state is set to Disable parameter changes made via the serial link are not retained on power down The non volatile save state is not retained on power down and must be reset to the required state each time the inst...

Page 26: ...24 NOTES ...

Page 27: ...auge and absolute pressure measurement Also liquid level and temperature I to P Converters and Field Indicators Flow Metering Magnetic Flowmeters Electromagnetic insertion type probes and watermeters Turbine Flowmeters Wedge Flow Elements Mass Flow Meters Transmitters sensors controllers and batch display units Level Control Submersible Capacitance Conductivity Pneumatic Instrumentation Transmitte...

Page 28: ...75 Lockheed Way Carson City NV 89706 USA Tel 1 775 883 4366 Fax 1 775 883 4373 ABB has Sales Customer Support expertise in over 100 countries worldwide www abb com The Company s policy is one of continuous product improvement and the right is reserved to modify the information contained herein without notice Printed in UK 08 02 ABB 2002 ...

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