M2 Transmitter for 12 VDC Operation Operator’s Manual Part Number: 71-0115RK Revision: H Released: 4/3/14 RKI Instruments, Inc. www.rkiinstruments.
WARNING Read and understand this instruction manual before operating transmitter. Improper use of the transmitter could result in bodily harm or death. Periodic calibration and maintenance of the transmitter is essential for proper operation and correct readings. Please calibrate and maintain this transmitter 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 M2 Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 About this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 7: Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 1: Introduction Overview This chapter briefly describes the M2 Transmitter. This chapter also describes the M2 Transmitter Operator’s Manual (this document). Table 1 at the end of this chapter lists the specifications for the M2. About the M2 Transmitter The M2 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 M2. Table 1: M2 Specifications Target Gas/Detection Range Combustible (LEL) Gas: 0 - 100% LEL, 1% LEL increments Alarm Settings* • Alarm 1: 10 %LEL • Alarm 2: 50 %LEL Construction (housing) Explosion-proof Junction Box, NEMA 4 Area Classification Explosion-proof for Class I, Groups B, C, and D (LEL and toxic versions) Sampling Method Diffusion Input Power 10.8 - 14.
Chapter 2: Description Overview This chapter describes external and internal components of the M2 Transmitter. External Description This section describes the junction box and all external components of the M2 transmitter. 3/4 NPT Conduit Hub Junction Box Cover Mounting Slot (2x) Magnetic Wand Window Detector (Catalytic LEL Detector Shown) Figure 1: M2 External Components Junction Box The M2’s cast aluminum junction box is dust and weather resistant.
Magnetic Wand The magnetic wand is a short plastic rod with a magnet in one end. It is used to actuate the magnetic control switches on the control PCB while the junction box cover is still installed so that non-intrusive calibration can be performed. LEL Detector The LEL detector senses the target gas and is mounted in a 3/4” conduit hub on the right bottom side of the M2. The LEL detector has a 1/2” NPT thread and requires a 3/4”NPT x 1/2”NPT reducer to mount it in the detector hub.
Terminal PCB The terminal PCB is encapsulated in epoxy for protection against moisture and physical damage. It is mounted into the rear of the junction box with three standoffs and rests on a thin layer of foam. A banana jack is screwed into each of the standoffs and used for mounting the control PCB.
Control PCB The LCD display and control switches are located on the control PCB. It is installed on top of the terminal PCB by lining up its three spacing standoffs with the banana jacks in the terminal PCB mounting standoffs and pushing it onto the banana jacks. The jacks retain the control PCB. LCD Display The LCD display is located at the top of the control PCB. It indicates the current gas reading and displays messages and parameters in the M2’s programs.
Status LEDs The M2 includes five status LEDs that are located above the display (see Figure 2). • Fail LED The fail LED turns on when the M2 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 M2 is experiencing an alarm 1 condition. • Alarm 2 LED The alarm 2 LED is on when the M2 is experiencing an alarm 2 condition.
Chapter 3: Installation & Startup Overview This chapter describes procedures to mount the M2 Transmitter in the monitoring environment and wire it to input power and devices. Mounting the M2 Transmitter 1. 2. Select a mounting site that is representative of the monitoring environment. Consider the following when you select the mounting site. • Select a site where the M2 is not likely to be bumped or disturbed.
Wiring the M2 Transmitter WARNING: Always verify that the power source is OFF before making any wiring connections. 2. Grasp the control PCB by its edges. 3. Gently pull until the control PCB is pulled away from the banana jacks. Take care not to pull too hard and damage the cable which connects the control and terminal PCB’s. 4. Let the control PCB hang by the cable. The terminal strips are now visible on the terminal PCB. The control PCB may be left hanging while wiring is done.
be used, use a two or three conductor shielded cable or two or three wires in conduit for connections to the power/signal terminal strip depending on whether or not the signal (S) terminal is used. Table 3: Wire Size for PWR/SIG Connections Max Distance to Controller w/ 18 Gauge Wire 2,500 ft. Max Distance to Controller w/16 Gauge Wire 5,000 ft. • 8,000 ft. If the PWR/SIG connections and one or more relays are used, route the connections to the M2 in conduit.
8. Re-install the control PCB (and ribbon cable if necessary). Be sure the ribbon cable is routed down below the control PCB so it will not be damaged by the cover when it is screwed back on. 9. Secure the junction box cover to the junction box. 10. Make controller, device, and relay connections as appropriate.
control switch button, touch the magnet in the end of the magnetic wand to the M2’s glass cover directly above the magnetic switch you wish to actuate. Touching the glass and removing the wand is the same as pressing and releasing a button. Touching the glass and keeping the wand in place is the same as pressing and holding a button. WARNING: NOTE: The M2 is not an active gas monitoring device during the calibration procedure. The 4-20 mA output signal will “freeze” at 3.
Chapter 4: Operation Overview This chapter describes the M2 in normal operation. This chapter also describes the M2 in alarm 1, alarm 2, and fail conditions and suggests response to these conditions. Normal Operation Normal operation is defined as follows: • The start-up procedure is complete. • The M2 is not indicating an alarm 1, alarm 2, or fail condition. • The M2 is not in Calibration, Configuration, or Gas Type modes.
• When the M2 is in its warm-up period, the signal output will be fixed at 3.5 mA (zero). • When the M2’s gas type is changed, the M2 will enter Configuration Mode for you to verify the parameter settings. When you exit Configuration Mode, the display will indicate NEEDS CALIBRATION and will continue to indicate this until Calibration Mode is entered and a calibration is performed. In this situation, the signal output will be fixed at 3.
NOTE: You can select normally energized (N. EN) or normally de-energized (N. DEEN) alarm 1 and alarm 2 relay settings in Configuration Mode. The following sections describe the standard factory setting for these relays which is N. DE-EN. The fail relay is factory set as N. DE-EN and is not user-adjustable. Alarm 1 Condition Alarm 1 Condition Indications When the gas reading reaches the alarm 1 setpoint, the M2 senses an alarm 1 condition.
NOTE: If the ENTER button is pressed while the M2 is in an alarm 2 condition, the A2 LED will flash but all other indications will remain unchanged. You cannot de-energize the alarm 2 relay until the gas reading falls below the alarm 2 setpoint. Fail Condition Fail Condition Indications The M2 indicates a fail condition for any of the following: • The detector wiring is disconnected or incorrectly connected. • The display reading is -10% of full scale or lower.
Chapter 5: Configuration Mode Overview This chapter describes how to view and change M2 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 M2 automatically returns to normal operation. NOTE: If the M2 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) (See “M2 Specifications” on page 2) The gas reading at which the M2 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.
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 setting for a combustible detector is 2.0% LEL, the M2 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 the Gas Type Mode to select the M2’s gas type. The gas type determines the target gas and detection range. The Gas Type Mode includes a 5-minute time-out feature. If you do not press a button for 5 minutes, the M2 automatically returns to normal operation. NOTE: If the M2 enters normal operation because of a program time-out, it enters a warm-up period just as it does when it is first turned on. Selecting the Gas Type 1.
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. The display will ask ABORT? YES/NO. Press the UP/YES button. The M2 will return to normal operation without changing the gas type. To save the gas type, press and release the UP/YES button.
Chapter 7: Maintenance Overview This chapter describes procedures for performing preventive maintenance, troubleshooting, calibrating the M2, and replacing field replaceable parts. Preventive Maintenance This section describes a recommended preventive maintenance schedule to ensure the optimum performance of the M2. It includes daily, monthly, and quarterly procedures. Daily Verify a display reading of zero. Investigate significant changes in the reading.
11. If external alarms have been disabled, enable them when the display returns to a normal fresh air reading. 12. Store the components of the calibration kit in a safe place. Quarterly Calibrate the M2 as described in “Calibration” on page 25. See “Calibration Frequency” on page 25 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 M2.
Table 7:Troubleshooting the Combustible Gas Detector (Continued) Condition Symptom(s) Probable Causes Recommended Action Flickering Display The display reading flickers often. • The M2 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 M2 wiring is properly shielded. See “Wiring the M2 Transmitter” on page 9. 2.
Calibration Frequency Although there is no particular calibration frequency that is correct for all applications, a calibration frequency of every 3 to 6 months is adequate for most M2 applications. Unless experience in a particular application dictates otherwise, RKI Instruments, Inc. recommends a calibration frequency of every 3 months.
2. Screw the calibration cup onto the detector. 3. Connect the fixed flow regulator to the calibration cup using the sample tubing. Non-Intrusive Calibration If the M2 is installed in a classified area and non-intrusive calibration is required, follow the instructions below, but do not remove the junction box cover. Use the magnetic wand accessory to actuate the magnetic switches instead of pushing the control switch buttons.
8. Unscrew the zero air cylinder from the fixed flow regulator leaving the calibration cup on the detector. The M2 will continue to display the minimum gas response on the display and retain the response level in its memory. 9. Press and release the ENTER button. The M2 will perform a fresh air adjustment and the display will indicate SPAN w/Cal Gas?. NOTE: If the fresh air adjustment fails, see “Troubleshooting” on page 23 for recommended actions. Adjusting the Span Setting 1.
Replacing Components of the M2 Replacing LEL Detector 1. Turn off or disconnect power to the M2. 2. Remove the junction box cover. 3. Grasp the control PCB by its edges. 4. Gently pull until the control PCB is pulled away from the banana jacks. Take care not to pull too hard and damage the cable which connects the control and terminal PCB’s. 5. Let the control PCB hang by the cable. The terminal strips are now visible on the terminal PCB. The control PCB may be left hanging while wiring is done.
Chapter 8: RS-485 Modbus Output Overview This chapter describes the M2’s RS-485 Modbus output and how to configure the M2 to make use of it. It also discusses how to wire the M2 into a Modbus system. The M2 provides an RS-485 serial communications interface. It is a Modbus Slave Device, supporting 2-wire RS-485 Modbus RTU serial communications.
installed in an M2 that is at the end of a Modbus line. Any M2 in a Modbus system that is not at the end of a line must have the termination jumper removed (see Figure 6 & Figure 7 below). ID = 128 Modbus Master M2 Termination Jumper Installed RS-485 RS-485 Up to 128 M2s can be connected without a repeater.
Using the M2 in a 4-wire Modbus System The M2 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. • Connect these D0 and D1 signals and the common wire from the controller to the 2wire Modbus Network of M2s.
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 M2 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 M2 supports Function Code 03: Read Holding Registers and Function Code 16: Write Registers. The register assignments detailed below were implemented in M2 firmware version 5.0. Please see revision 0 of the 12 V M2 manual if you have an M2 with a firmware version previous to 5.0. WARNING: Do not attempt to use registers according to the instructions below with units that have firmware versions previous to 5.0.
Table 11: Register 2, Operating State, Alarms & Relays Bit & Field Assignments (Continued) Bit(s) Value [11] Gas Type Change 0=Not Changed 1=Changed [10] Configuration Change 0=Not Changed 1=Changed [9] Calibration Activity Flag 0=No Calibration Activity 1=Calibration Activity Has Occurred [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 A
Register 12 Register 12 is the range (full scale readout). Register 13 Register 13 is the alarm 1 set point. The decimal point location is the same as specified in Register 1. Register 14 Register 14 is the alarm 2 set point. The decimal point location is the same as specified in Register 1. 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.
Register 30 Register 30 is the alarm 2 relay reset. 0=Latching 1=Self-Resetting Register 31 Register 31 is the alarm 2 ON delay. Integer values are in seconds. Register 32 Register 32 is the alarm 2 OFF delay. Integer values are in seconds. Register 33 Register 33 is zero suppression. Toxics and LEL: 0%-6% of full scale 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 39 Register 39 is the auto-zero disable. 0=AutoZero Enabled 1=AutoZero Disabled Register 40 Register 40 is the remote configuration register access level. 0=None 1=Alarm Reset Function Code 16: Write Registers There are 21 registers in Function Code 16 that can be used to write to the M2. 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.
Parts List Table 13 lists replacement parts and accessories for the M2 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 M2’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 M2 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 8 below for field wiring connections to the M2.
Appendix C: Function Code 16 Registers The M2 supports Function Code 16 that allows writing to the M2. There are 21 registers in this Function Code. The register assignments detailed below were implemented in M2 firmware version 5.0. Please see revision 0 of the 12 VDC M2 manual if you have an M2 with a firmware version previous to 5.0. WARNING: Do not attempt to use registers according to the instructions below with units that have firmware versions previous to 5.0.
Register 9 Register 9 is the alarm 2 relay state. 0=Normally De-Energized 1=Normally Energized Register 10 Register 10 is the alarm 2 relay reset. 0=Latching 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 Value must be an integer. Any decimals are omitted.
Bit(s) [0] Value & Field Write “1” to this bit to clear “Configuration Changed” flag Register 20 Register 20 is the AutoZero Disable. 0=AutoZero Enabled 1=AutoZero Disabled Register 21 Register 21 is the Remote Configuration Register.
