65-2649RK-CH4-4 M2A Transmitter Operator’s Manual Part Number: 71-0318RK Revision: P1 Released: 5/16/14 RKI Instruments, Inc. www.rkiinstruments.
WARNING Read and understand this instruction manual before operating instrument. Improper use of the gas monitor could result in bodily harm or death. Periodic calibration and maintenance of the gas monitor is essential for proper operation and correct readings. Please calibrate and maintain this instrument regularly! Frequency of calibration depends upon the type of use you have and the sensor types.
Product Warranty RKI Instruments, Inc. warrants gas alarm equipment sold by us to be free from defects in materials, workmanship, and performance for a period of one year from date of shipment from RKI Instruments, Inc. Any parts found defective within that period will be repaired or replaced, at our option, free of charge.
Table of Contents Chapter 1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 About the M2A Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 About this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 7: Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 1: Introduction Overview This chapter briefly describes the 65-2649RK-CH4-4 M2A Transmitter. This chapter also describes the 65-2649RK-CH4-4 M2A Transmitter Operator’s Manual (this document). Table 1 at the end of this chapter lists the specifications for the M2A. About the M2A Transmitter The M2A transmitter is a fixed mount, continuous-monitoring detector head. All user adjustable parameters may be accessed using push button switches.
Specifications Table 1 lists specifications for the M2A. Table 1: M2A Specifications Target Gas/Detection Range Methane: Alarm Settings (Alarm 1/Alarm 2) 10 %LEL/50 %LEL Construction (housing) Explosion-proof Junction Box, NEMA 4 Area Classification Explosion-proof for Class I, Groups B, C, and D Sampling Method Diffusion Input Power 10 - 30 VDC Controls • Three push button switches • Three magnetic switches for non-intrusive calibration Weight 5.5 lbs.
Chapter 2: Description Overview This chapter describes the components of the M2A transmitter. The transmitter is a 4 - 20 mA type detector head. It consists of the IR LEL detector, calibration adapter/splash guard, terminal PCB, the M2A junction box, and the detector junction box. The two junction box configuration is intended for situations where the detector needs to be installed at an inaccessible location.
M2A Junction Box The M2A’s cast aluminum junction box protects the terminal PCB and wiring connections made to the terminal PCB. Use the three 3/4 in. conduit hubs to wire the remotely installed IR LEL detector and connect wiring from an external device, typically an RKI controller. The top hub is shipped with a factory installed and sealed conduit plug to avoid leaks into the junction box. If necessary, the conduit plug can be removed and the top hub can be used for wiring.
Internal Description This section describes the internal components of the M2A. The internal components of the M2A include the terminal PCB which provides for all the wiring connections to the M2A and the control PCB which displays the gas reading and has the control buttons.
Power/Signal Terminal Strip The power/signal terminal strip is a three position plug-in style terminal strip located at the top of the left terminal column. It is used to connect 24 VDC power to the M2A and to connect the 4 - 20 mA output signal to a device. The signal output, the S terminal, does not have to be connected for the M2A to function.
installation. See “Chapter 8: RS-485 Modbus Output” on page 36 for a description of using the M2A in a Modbus system. Ground Jumper A two pin header with a jumper installed is located along the left side of the terminal PCB. Leave this jumper installed unless directed to remove it for a Modbus installation. See “Chapter 8: RS-485 Modbus Output” on page 36 for a description of using the M2A in a Modbus system. Control PCB The OLED display and control switches are located on the control PCB.
Status LEDs The M2A includes five status LEDs that are located above the display (see Figure 2). • Fail LED The fail LED turns on when the M2A is experiencing a fail condition. A fail condition can be caused by a detector failure or low detector signal. • Alarm 1 LED The alarm 1 LED is on when the M2A is experiencing an alarm 1 condition. • Alarm 2 LED The alarm 2 LED is on when the M2A is experiencing an alarm 2 condition.
Chapter 3: Installation & Startup Overview This chapter describes procedures to mount the M2A Transmitter in the monitoring environment and wire it to input power and devices. Mounting the M2A Transmitter 1. 2. Select a mounting site that is representative of the monitoring environment. Consider the following when you select the mounting site. • For the M2A junction box, select a site where the junction box is not likely to be bumped or disturbed.
3/4 N PT Fem ale 2.70 .38 3.65 9.00 M A X Rubb er S pacer, 3X J-Bo x IR LE L Detec tor 5.25 Cali bration A dapter/ S plash G uard .75 Figure 5: Outline & Mounting Dimensions, Detector Junction Box 3. Install 3/16 inch I.D. flexible polyurethane tubing to the fitting at the bottom of the calibration adapter/splash guard and route it to an accessible area that is close to the M2A junction box. See the “Parts List” on page 46 for available tubing.
Wiring the M2A Transmitter WARNING: Always verify that the power to the M2A is off before you make wiring connections. 1. Confirm that no power is being applied to the M2A. 2. Remove the detector junction box’s cover from the junction box. 3. Remove the M2A junction box’s cover from the junction box. 4. Grasp the control PCB by its edges. 5. Gently pull until the control PCB is pulled away from the banana jacks.
12. Pull out the detector terminal strip and connect the four wires to the terminal strip as follows (see Figure 6). • Connect the wire corresponding to the detector’s red wire to the LEL “R” terminal. • Connect the wire corresponding to the detector’s white wire to the LEL “W” terminal. • Connect the wire corresponding to the detector’s green wire to the LEL “G” terminal. • Connect the wire corresponding to the detector’s black wire to the LEL “B” terminal.
14. If shielded cable is used between the detector junction box and the M2A junction box, connect the cable’s drain wire to an available chassis (earth) ground at the M2A junction box. Do not connect the shield drain wire at the detector junction box. 15. Guide multi conductor shielded cable or cables or wires in conduit through the side conduit hub of the M2A junction box.
See Figure 7 below for field wiring connections to the M2A. Alarm Device Power B (24 VDC) - A See Modbus Wiring B C RS 485 R See Detector Wiring Alarm 1 Alarm Device C NC NO ALARM 1 4 - 20 mA In (S) Fail Alarm Device Alarm 2 Alarm Device C NC NO ALARM 2 - S + PWR/SIG (24 VDC) + C NC NO FAIL Cable Shield W G LEL RKI Controller Terminals Typical Alarm Wiring Shown Figure 7: Wiring the M2A Junction Box to a Controller and Alarm Devices 16.
Start Up Introducing Incoming Power 1. Complete the installation procedures described earlier in this manual. 2. Verify that all wiring connections are correct and secure. 3. Turn on the incoming power. 4. If necessary, turn on the controller or other monitoring device that is connected to the M2A. 5. The OLED display will indicate the firmware version when the M2A is first powered up and will then count down a one minute warm-up period before normal operation begins.
WARNING: NOTE: 1. The M2A is not an active gas monitoring device during the fresh air adjustment procedure. The 4-20 mA output signal will “freeze” at 3.5 mA and all relays will remain in their non-alarm state while the M2A is in Calibration Mode. The output signal will not indicate current readings and the relays will not resume operating normally until the M2A is in normal operation again.
Chapter 4: Operation Overview This chapter describes the M2A in normal operation. This chapter also describes the M2A in alarm 1, alarm 2, and fail conditions and suggests responses to these conditions. Normal Operation Normal operation is defined as follows: • The start-up procedure is complete. • The M2A is not indicating an alarm 1, alarm 2, or fail condition. • The M2A is not in Calibration, Configuration, or Gas Type modes.
4 - 20 mA Signal Output Operation The output at the S terminal of the power/signal terminal strip is a 4 - 20 mA signal that corresponds to the detection range of the M2A. During normal operation, this signal tracks the gas concentration on the OLED display. There are several circumstances where the signal output will not track the display reading but will behave as follows: • When the M2A is in its warm-up period, the signal output will be fixed at 3.5 mA (zero).
Table 4: Visual and Audible Alarm Indications Condition Low Power * Cause Visual Indication(s) DC power source less than 9.5 volts. • F LED is on • LowPower message and actual voltage of incoming DC power 1If the M2A is in both an alarm 1 and an alarm 2 condition, both alarm LEDs are on and the display alternates between the gas reading and the ALMS 1&2 message. NOTE: You can select normally energized (N. EN) or normally de-energized (N.
NOTE: If the M2A is in both an alarm 1 and alarm 2 condition, both the A1 and A2 LEDs will be on, the gas reading will alternate with the ALMS 1&2 message, and both alarm relays will energize. Responding to an Alarm 2 Condition 1. Follow your established procedure for a high level combustible gas condition. 2. After the gas reading falls below the alarm 2 setpoint, press the ENTER button to reset the alarm circuit.
NOTE: The low power alarm cannot be cleared using the ENTER button. When the voltage increases to 10.0 volts, the low power alarm is cleared and the M2A will begin its warm-up sequence. Responding to a Low Power Condition 21 1. Determine and correct the cause of the low power condition. 2. When the input power increases above 10.0 volts, the M2A will begin its warm-up sequence. 3. Verify that the M2A enters normal operation after its warm-up sequence. If necessary, perform a fresh air adjustment.
Chapter 5: Configuration Mode Overview This chapter describes how to view and change M2A parameters using Configuration Mode. It is accessed using the program buttons. Configuration Mode includes a 5-minute time-out feature. If you do not press a control button for 5 minutes, the M2A automatically returns to normal operation. NOTE: If the M2A returns to normal operation because of a time-out, it enters a warmup period just as it does when it is first turned on.
Table 5: Configuration Parameters Parameter (Factory Set Value) Description ALARM-1 (level) (10% LEL) The gas reading at which the M2A initiates an alarm 1 condition. ALARM-1 (activation) (Increase) Indicates if the alarm 1 circuit is activated by gas readings increasing (Increase) or decreasing (Decrease) to the ALARM-1 Level. ALARM-1 (relay action) (N. DE-EN) If set as N. DE-EN, the alarm 1 relay is de-energized in normal operation and energizes when an alarm 1 condition is initiated. If set as N.
Table 5: Configuration Parameters (Continued) Parameter (Factory Set Value) Description ZeroSupp (2% LEL) The zero suppression feature helps prevent “jumpy” readings near the fresh air reading. For example, if the zero suppression is 2.0% LEL, the M2A will display a reading of 0% LEL for gas readings from -2% LEL to 2% LEL. It is settable from 0 to 6% of the detection range. FILTER (5 secs) The filter feature helps “smooth out” jumpy or noisy signals from the detector.
Chapter 6: Gas Type Mode Overview This chapter describes how to use Gas Type Mode to select the M2A’s gas type. The gas type determines the target gas and detection range. CAUTION: The 65-2649RK-CH4-4 M2A is factory setup for methane (CH4). Do not change the Gas Type setting. Gas Type Mode includes a 5-minute time-out feature. If you do not press a button for 5 minutes, the M2A automatically returns to normal operation.
Table 6: Gas Types Gas Type Choices Detection Range METHANE 0 - 100% LEL CO2 0 - 5,000 ppm CO2 0 - 2,000 ppm CO2 0 - 100% volume CO2 0 - 50.0% volume CO2 0 - 5.00% volume NH3 0 - 5.00% volume NH3 0 - 2.00% volume 4. When the desired target gas is on the display, press and release the ENTER button. The display will ask SAVE IT? YES/NO. 5. To discard the gas type change, press and release the DOWN/NO button. The display will ask DO OVER? YES/NO. Press the DOWN/NO button.
NOTE: 27 When calibrating an M2A after changing the gas type, the M2A will not ask if you want to calibrate, or whether you want to perform a fresh air adjustment, span adjustment or zero adjustment. Since a complete calibration is required, the calibration sequence will proceed without asking if you want to perform certain operations.
Chapter 7: Maintenance Overview This chapter describes procedures for performing preventive maintenance, troubleshooting, calibrating the M2A, and replacing field replaceable parts. Preventive Maintenance This section describes a recommended preventive maintenance schedule to ensure the optimum performance of the M2A. It includes daily, monthly, and biannual procedures. Daily Verify a display reading of 0% LEL. Investigate significant changes in the reading.
10. If external alarms have been disabled, enable them when the display returns to a normal fresh air reading. 11. Store the components of the calibration kit in a safe place. Biannually Calibrate the M2A as described in “Calibration” on page 32. See “Calibration Frequency” on page 31 for a discussion of calibration frequency guidelines. Troubleshooting The troubleshooting guide describes symptoms, probable causes, and recommended action for problems you may encounter with the M2A.
Table 7:Troubleshooting the IR LEL Detector (Continued) Condition Symptom(s) Probable Causes Recommended Action Flickering Display The display reading flickers often. • The M2A is experiencing false readings due to RFI or EMI. • The noise filter setting is too low. • The zero suppression setting is too low. • The display screen is malfunctioning. 1. Verify that the M2A wiring is properly shielded. See “Wiring the M2A Transmitter” on page 11. 2. Verify that the detector wiring is correct and secure.
Calibration Frequency Although there is no particular calibration frequency that is correct for all applications, a calibration frequency of every 6 months is adequate for most infrared combustible gas transmitter applications. Unless experience in a particular application dictates otherwise, RKI Instruments, Inc. recommends a calibration frequency of every 6 months.
Calibration This section describes how to calibrate the M2A transmitter. It includes procedures to prepare for calibration, enter Calibration Mode, adjust the fresh air (zero) setting, adjust the span setting, and return to normal operation. WARNING: The M2A is not an active gas monitoring device during the calibration procedure. The 4-20 mA output signal will “freeze” at 3.5 mA and all relays will remain in their non-alarm state while the M2A is in Calibration Mode.
Adjusting the Fresh Air Reading 1. While in normal operation, press and hold the UP/YES button for 5 seconds to enter Calibration Mode. Release the button when the following screen appears. Calib? YES/NO 2. If you want to continue with calibration, press and release the UP/YES button. The display will indicate the target gas and CAL Mode for a few seconds before showing FreshAir Adjust?. If you want to exit Calibration Mode, press and release the DOWN/NO button.
Response Time” on page 31. 5. Turn the regulator knob clockwise to close it. 6. Unscrew the calibration gas cylinder from the fixed flow regulator. The M2A will continue to display the maximum gas response on the display and retain the response level in its memory. 7. Adjust the gas reading up or down to match the calibration gas cylinder concentration by using the UP/YES and DOWN/NO buttons, then press and release the ENTER button. 8. The M2A will perform a span operation.
NOTE: Allow the replacement detector to warm up for 15 minutes before you continue with the next step. 11. Calibrate the replacement detector as described in “Calibration” on page 32.
Chapter 8: RS-485 Modbus Output Overview This chapter describes the M2A’s RS-485 Modbus output and how to configure the M2A to make use of it. It also discusses how to wire the M2A into a Modbus system. The M2A provides an RS-485 serial communications interface. It is a Modbus Slave Device, supporting 2-wire RS-485 Modbus RTU serial communications. Wiring the M2A in a Modbus System The M2A is a 2-wire Modbus RTU device.
Recommended Modbus Wiring The recommended Modbus wiring for the M2A is illustrated in Figure 8 below. In this configuration, 5 wires are used for wiring the M2A into a Modbus system. Figure 8 also illustrates typical alarm device wiring. The ground jumper must be removed in this wiring configuration.
Adding an M2A to an Existing M2 Modbus Installation with Alternate Wiring An M2A can be wired into an existing M2 Modbus system. The shape of the terminal PCB will be different but the wiring connections are identical and the ground jumper on the M2A must still remain installed. Termination Jumper The M2A includes a 2-pin termination header (see Figure 2) that is used when the M2A is used in a Modbus system. Every M2A is supplied with a termination jumper (a jumper block) installed onto this header.
Using the M2A in a 4-wire Modbus System Although the M2A is a 2-wire Modbus RTU device, it can be used with a 4-wire Modbus controller if the system wiring is modified as follows: • Connect the controller’s TxD0 and RxD0 wires together and use this connection as the 2-wire Modbus D0 signal. • Connect the controller’s TxD1 and RxD1 wires together and use this connection as the 2-wire Modbus D1 signal.
Table 9: Configuration Parameters Modbus Mode Parameter Available Settings & Description Enabled/Disabled Can be set to ENABLED or DISABLED (factory setting). Enables or disables the Modbus output. Slave ID The Slave ID can be set to values from 1 (factory setting) to 247. The M2A will only receive messages from the Master which are addressed to this Slave ID (except for broadcast messages which are received by all slaves).
Supported Modbus Functions The M2A supports Function Code 03: Read Holding Registers and Function Code 16: Write Registers. Function Code 03: Read Holding Registers There are a total of 40 registers available to be read via this Function Code. Registers 1 - 2 The format (bit & field assignments) for registers 1 - 2 is shown below in Table 10 Table 11.
Table 11: Register 2, Operating State, Alarms & Relays Bit & Field Assignments (Continued) Bit(s) Value [8] Fail Status 0 = Fail Not Asserted 1 = Fail Asserted [7:6] Alarm 2 Status 0 = No Alarm 1 = Unacknowledged Alarm 2 = Acknowledged Alarm 3 = Unused Code [5:4] Alarm 1 Status 0 = No Alarm 1 = Unacknowledged Alarm 2 = Acknowledged Alarm 3 = Unused Code [3] Overscale Status 0 = Not Overscale 1 = Overscale [2] Fail Relay Status 0 = Not Energized 1 = Energized [1] Alarm 2 Relay Status 0 = Not Ene
Registers 15 - 19 Registers 15 - 19 are the Gas Name ASCII String (NULL Terminated). Registers 20 - 22 Registers 20 - 22 are the Gas Units String (NULL Terminated). Register 23 Register 23 is the alarm 1 trigger. 0=Decreasing 1=Increasing Register 24 Register 24 is the alarm 1 normal relay state. 0=Normally De-Energized 1=Normally Energized Register 25 Register 25 is the alarm 1 relay reset. 0=Latching 1=Self-Resetting Register 26 Register 26 is the alarm 1 ON delay. Integer values are in seconds.
Register 33 Register 33 is zero suppression. Toxics and LEL: 0%-6% of full scale Oxygen: 0%-0.7% Oxygen The decimal point location is the same as specified in Register 1. Register 34 Register 34 is noise filter. Integer values in seconds. 0-60 in 5 second increments. Register 35 Register 35 is calibration timeout in minutes (5, 10, 15, 20, 25, or 30). Register 36 Register 36 is calibration month (upper byte) and day (lower byte). This is zero based (e.g. January=0 and the 1st=0).
Function Code 16: Write Registers There are 21 registers in Function Code 16 that can be used to write to the M2A. This manual only describes Register 16 because it can be used to reset an alarm condition. For a complete description of Function Code 16, request Appendix C from RKI Instruments, Inc. Register 16 Register 16 performs the same function as the ENTER button on the M2A. It is useful for remotely silencing alarms. With the M2A in an alarm condition, bit [0] can be used to silence it.
Parts List Table 13 lists replacement parts and accessories for the M2A Transmitter. Table 13: Parts List Part Number Description 06-1248RK Calibration kit sample tubing (3/16 in. x 5/16 in.
Appendix A: Control Button Quick Reference Guide The M2A’s control buttons allow access to operational modes, resetting of alarms, and display of the Information Screen. Table 14 shows which button combinations perform these functions and which parameters are available for adjustment while in the operational modes. While in these modes, display prompts showing a “?” require you to respond by pressing either the UP/YES (for yes) or DOWN/NO (for no) button.
Appendix B: PLC and DCS Device Wiring The M2A can be wired to a PLC or DCS device if desired. 1. Guide multi conductor shielded cable or cables or wires in conduit through the top conduit hub of the junction box. The number of cables or wires needed will depend on whether any relays are used and whether the Modbus output is used.
See Figure 12 below for field wiring connections to the M2A.
Appendix C: Function Code 16 Registers The M2A supports Function Code 16 that allows writing to the M2A. There are 21 registers in this Function Code. Register 1 Register 1 is the alarm 1 set point. Value must be an integer. Any decimals are omitted. Register 2 Register 2 is the alarm 1 trigger. 0=Decreasing 1=Increasing Register 3 Register 3 is the alarm 1 relay state. 0=Normally De-Energized 1=Normally Energized Register 4 Register 4 is the alarm 1 relay reset.
1=Self-Resetting Register 11 Register 11 is the alarm 2 ON delay. Integer value is in seconds. Register 12 Register 12 is the alarm 2 OFF delay. Integer value is in seconds. Register 13 Register 13 is the zero suppression. Toxics and LEL: 0%-6% Full Scale Oxygen: 0%-0.7% Oxygen Value must be an integer. Any decimals are omitted. Register 14 Register 14 is the noise filter. Integer value is in seconds (0-60 in 5 second increments). Register 15 Register 15 is the calibration timeout.
Register 19 Register 19 is for clearing change flags. When parameters are changed at the M2A, a flag is raised at the controller. This register can be used to clear those flags. Table 16: Register 19, Clear Change Flags Bit(s) Value & Field [15:2] Unused [1] Write “1” to this bit to clear “Gas Type Changed” flag [0] Write “1” to this bit to clear “Configuration Changed” flag Register 20 Register 20 is the AutoZero Disable.
