Integrating the MDT SMART Link-485 Sensor Application Note #32

Transcription

1 5 Gould Road, PO Box 2155 New London, NH USA Voice: (603) Integrating the MDT SMART Link-485 Sensor Application Note #32 Overview MDT s SMART MPBX is a flexible borehole extensometer with up to six anchor points and an integrated electronic readout head. As each anchor moves, fiberglass rods within the MPBX produce a very precise change in resistance at the wiper terminals. This resistance change is converted to a voltage, relative to a reference voltage. The displacement is calculated as a ratio of this data. The displacement data from each anchor is interpreted, and rock movement mapped. The MDT SMART Link-485 connects to the MPBX readout head and provides a 2 wire RS-485 half duplex serial interface which can be connected to a Campbell Scientific CR6 Datalogger via a RSCOM2A RS-485 to RS-232 converter (provided by RESmith). The goal of this document is to walk through the configuration of an MDT SMART Link-485 and configuring MultiLogger to ingest the data being produced by the MDT SMART MPBX. System Wiring and Configuration A converter is typically required to convert the RS-485 output of the MDT SMART Link-485 to RS-232. Figure 1 is the wiring diagram connecting a SMART Link-485 to a Campbell Scientific CR6 using an RESmith RSCOM2A converter. The RSCOMA2A provides a low-cost, highly configurable signal converter. (Figure 1 - Connection path between CR6, RSCOM2A and two SMART Link-485. You can have one or more SMART Link-485s all connecting to the same RSCOM2A.) Note - In Figure 1, wiring for COM1 is used. Use alternate ports for other COM ports. Integrating the MDT SMART Link-485 1

2 (Figure 2 - Side view of RSCOM2A) Note - Two of the internal jumpers inside the RSCOM2A converter need to be moved from their factory default position to function properly with SMART Link-485, shown in Figure 3. Function Test (Figure 3 - RSCOM2A Converter showing updated jumper positions) Prior to completing final connection to the CR6 Datalogger, it is recommended to test the operation of the SMART Link-485. Ideally this is completed prior to grouting the unit into the drill hole. (Figure 4 - Components needed for testing operation of SMART Link-485) A 12V power source is required for the SMART Link-485 and the RSCOM2A, a 12V battery works well. Wiring connection paths are shown previously in Figure 1. The RSCOM2A ships with a ribbon cable with an RJ11 connector on one end and a 9-pin serial connection on the other. First, connect the RJ11 to the RSCOM2A and the serial connection to a straight-through serial cable connected to a serial port on a computer. Next launch a terminal emulation program (HyperTerminal was used for this document) on a computer. Integrating the MDT SMART Link-485 2

3 Configure the COM port as follows: Bits per second (baud rate): Data bits: 8 Parity: None Stop bits: 1 Flow Control: Hardware (Figure 5 - Terminal emulation program configuration) The SMART Link-485 will be in a low power, sleep mode and it takes a sequence of 2 commands (one to wake the unit and one to return data). This is desirable to avoid accidentally awakening the SMART-Link 485 in electrically noisy environments. The command you need to send to the MDT SMART Link-485 is the serial number of the SMART Link-485 concatenated with RDAAM followed by a carriage return and line feed<cr><lf>. (Figure 6 - Location of serial number on SMART Link-485) Issuing a RD command triggers a new data sample and produces a response which includes the initial reading, the current reading and the delta. The first A in the RDAAM command tells the system to send data from all ports and the second A in the command tells the system to send results for all channels. The M is telling the system to respond in metric units or millimeters. This command needs to be sent 2 times in quick succession (less than 1 second). It is recommended that the command be copied to the clipboard so that it can be pasted to the HyperTerminal session followed by the <Enter> key then quickly pasted again to the HyperTerminal session followed by the <Enter> key. If the system is working properly you should see something like the example response from the SMART Link-485 in Figure 7 after sending the second command. Note - There is a separate serial number assigned to the extensometer which is returned in the response. In the example in Figure 6, the serial number of the SMART Link-485 is LK and the command sent in is LK180427RDAAM. The serial number of the extensometer is MDTC-M which is in the response, shown in Figure 7. Integrating the MDT SMART Link-485 3

4 The fields of the string in Figure 7 are as follows: (Figure 7 - Response from SMART Link-485) "S" - start of the sample/string/response. "MDTC-M " - the serial number of the extensometer connected to the SMART Link-485. "IDE" - indicates the location where the information about the MPBX was read from. The "E" indicates the SMART ID is external to the Link-485, this is usually the case when using SMART Link-485. If this had been "IDI", the "I" standing for "internal" would indicate that the information about the MPBX was read from within the Link-485 (an extra SMART ID is added inside the Link-485). This would be the case when the Link-485 is paired/bonded to a specific legacy instrument that does not have a SMART ID memory chip built in. The Link-485 would have the serial number of the MPBX penciled in on the label under the "Paired SMART Instrument SN". "23.5" - temperature in Celsius "645" - this is a legacy value for Voltage that MDT has kept for backwards compatibility issues. This value divided by 56 gives you volts DC. In the example 645/56 =11.5Vdc. "M" - precedes the first reading (position) and indicates Metric units. Three values following M - first value is the initial value, the second value is the current reading (this is the value that will be reported in MultiLogger ) and the third value is the delta. There are as many of these 3 value entries as there are sensors on the SMART Link-485 (in the example there are six). "AAM" - echo of the port, channel and unit command issued: All ports, All channels, Metric units. MultiLogger Configuration Typically, the Direct Connect Channel configuration would be used for configuring the SMART Link-485. However, since the number of Direct Connect Channels in a Campbell CR6 Datalogger are limited to 12 and each position requires a channel; if the system must read more than 2 MPBXs with 6 positions each, there would be insufficient channels. In this case, use a Multiplexer configuration, the following section details this configuration. Note - A gage type has been added to support reading the MDT SMART Link-485. Contact Canary Systems if your installation of software does not list the required gage types. Direct Connect Channel Configuration Add a Campbell CR6 MCU to the network, double-click to load the Logger form. Then, select the Direct Connect option on the Program tab, as shown in Figure 8. (Figure 8 - Program tab of the MultiLogger program configuration outlining the Direct Connect option) Integrating the MDT SMART Link-485 4

5 When configuring the Direct Connect Channels, select MDT SMART Link-485 as the Gage Type. (Figure 9 - Direct Connect Channel configuration form, note the Gage Type (Make Mode) selection for Channel 1) Subsequent channels would be configured with each SMART Link-485 position. Multiplexer Configuration (Figure 10 - Example of Direct Connect Channel configuration for channel 2) If more channels are required than can be supported using Direct Connect configuration then a multiplexer may be configured. The Multiplexer configuration simply acts as a placeholder for the measurements. Use the Multiplexers button on the Program tab to display the Configure Multiplexers form. (Figure 11 - MultiLogger Configure Program outlining the Multiplexers option) Integrating the MDT SMART Link-485 5

6 When configuring the Multiplexers, select Virtual as the Model and MDT SMART Link-485 as the Gage Type. (Figure 12 - Channel configuration when using Multiplexers) The Channels drop-down determines how many channel placeholders are available. Press the Edit Channels button to configure the channels. Note - Channel configuration is similar for Direct Connect and Multiplexers. Activating MultiLogger (Figure 13 - Channel configuration when using Multiplexers) Once all channels are configured select Start/Update to download the program and then Activate the logger. (Figure 14 - MultiLogger - Text Monitor) Integrating the MDT SMART Link-485 6

7 Appendix A. SMARTL Link-485 Pinouts and Color Codes 10 Position Female Pinout 10 Position Female 7 Position Male Pinout 7 Position Male MultiLogger and Canary Systems are Registered Trademarks of Canary Systems, Inc. Campbell Scientific is a Registered Trademark of Campbell Scientific, Inc. Integrating the MDT SMART Link-485 7