MTB-etc Installation and Operating Instructions

Digital outputs 1 through 8 are pilot duty and turn on to common ground when closed. Outputs 1 through 8 are rated at 500mA, 60V.

Mount the Modbus Terminal Board either on the bottom or the side of the main panel. The terminal board can be rail-mounted onto commercially available 32 or 35 mm DIN mounting rails. The operating temperature range of the Terminal Module is −40°F to +176°F (−40°C to +80°C).

Mount the pressure transducer in the panel or in a manifold or tube off of the engine. Do not expose the pressure transducer to temperatures above 221°F. (105°C). The second terminal module should be placed close to the first and the wire connecting them should be free of high-powered panel signals.

Mount the temperature transducer in a thermowell on the engine or machine. The actual sensor is located at the bottom of the transducer body; to ensure accuracy, the tip of the probe should be surrounded by the measured media. The center of the pickup face must line up with the center of each drilled hole as the disc rotates.

Connect the supply power wires to the 12-24Vdc input power terminals on the board, plus to terminal (+) and minus to terminal (−); power requirement is 12 to 24Vdc (10 watts max.). The DC− terminal must be connected to panel ground, which should be the same as engine ground. This is the return path for normally-open sensors and must be connected for proper operation. DO NOT ground this device directly to the ignition system common coil ground.

The sensor leads connect to the removable terminal strips on the terminal board. Any discrete sensor point can be wired for normally-open or normally-closed operation.

■ Normally-open (N/O) sensor switches are wired with one wire to the bottom terminal strip of the respective sensor number and the other to engine ground which should be the same as power minus (−). A short jumper from the bottom terminal to the top terminal must be connected for normally-open sensors. (see wiring diagrams)

■ Normally-closed (N/C) sensor switches are wired with one wire to the bottom terminal strip and the other to the top terminal strip of the respective sensor number. Note that the short jumper wire must be removed. Use a wire size between 16 AWG (max.) and 24 AWG (min.) to connect the sensor switches to the terminal strip connector. Strip the insulation back 3/8”; twist the exposed wires tightly together. Insert the exposed wire completely into the terminal strip and securely tighten the clamping screw. Wires running to sensor switches must be in good condition or replaced with new wires. When running wires, take care not to damage the insulation and take precautions against later damage from vibration, abrasion, or liquids in conduits. An explosion-proof conduit is not required. However; wires should be protected from damage by running them in a protective conduit or in sheaths where appropriate. In addition, it is essential that the following practices be adhered to:

A. Never run sensor wires in the same conduit with ignition wiring or other high energy wiring such as the AC line power.

B. Keep secondary wires to spark plugs and other high voltage wiring at least eight inches (200mm) away from sensor and sensor wiring.

C. Sensor switches may be connected to any passive device using contacts such as standard switch gauges, pressure or level switches. DO NOT connect sensor leads to any voltage producing element.

D. If it becomes necessary to check sensor switch to panel wiring with an ohmmeter or other checker, first DISCONNECT the plug-in terminal strips from the Terminal Module. Applying voltage to the Modbus terminal board through the sensor leads may damage the device. The area should be tested as non-hazardous before such testing commences.

For each analog monitored point, select a transducer—either an Altronic pressure or temperature transducer listed above or one that outputs a signal in the range of 0 to 5Vdc or 0 to 25mA. Mount as described above. Use cable assembly 693008-x or similar to wire transducer to the Modbus terminal board. An internal 5 volt sensor supply (500mA max.) is available to power the Altronic transducers; see wiring diagrams. If the 5 volt sensor supply exits the panel, it must be fused with a 0.5 ampere fuse. If 24Vdc powered sensors are used, the 24 volt supply to them must be fused appropriately. Take care not to damage the insulation when installing and take precautions against later damage from vibration, abrasion, or liquids in conduits.

Grounded or ungrounded type J or K thermocouples may be used. Use thermocouple extension wire of the same type as the thermocouple probe to connect to the terminal module. Use stranded thermocouple wire having a moisture-resistant insulation such as PVC; for higher ambient temperatures, Teflon or B-fibre insulated thermocouple wire is recommended. To ensure that an accurate signal is transmitted to the device, avoid any added junctions, splices and contact with other metals. On unused channels, leave the small jumper wire supplied with the system in place. Take care not to damage the insulation when installing and take precautions against later damage from vibration, abrasion, or liquids in conduits. In addition, it is essential that the following practices be adhered to:
A. Never run sensor wires in the same conduit with ignition wiring or other high energy wiring such as AC line power.
B. Keep secondary wires to spark plugs and other high voltage wiring at least eight inches (200mm) away from sensor and sensor wiring.
C. The slope and intercept values for thermocouples has been factory calibrated for each channel of the MTB-etc board. Ensure these values are not over-written when using thermocouples. Altronic maintains the factory calibration values associated with each board and are available upon request.
D. The user can change one Modbus register to switch from J to K thermocouples and visa versa. Set register 40189 to ‘0’ to make all channels J thermocouples and set it to ‘1’ to make them all channels K thermocouples. Individual channels may be selected to either J or K type thermocouples.

There is one RS-485 communication port: Use a two-conductor shielded cable of fine gauge stranded wire and connect the wires to the terminals marked A and B.

The T+ terminal on the Modbus terminal board can be used as a speed input. The T+ input is only for use with magnetic pickups. This input monitors a magnetic pickup monitoring an engine-mounted gear.

The Modbus Terminal Board is CSA certified for CLASS I, DIVISION 2, GROUPS C and D areas, when mounted in a suitable enclosure. In addition, the following requirements must be met (refer to NFPA standard No. 493):

■ The low voltage sensor switch wires within the panel enclosure must be kept at least two (2) inches away from other wiring. Run the sensor switch wires leaving the panel in a separate conduit from all other wiring and keep them separate.

■ Wiring to the sensors must have a grade of insulation capable of withstanding an AC voltage of 500 volts RMS.

■ Sensor wires must be run in separate conduits and junction boxes from high voltage wires such as ignition, fuel valve, and other high voltage wiring.

The configuration for setting up the communications are as follows:

BAUD RATE: 38.4K
DATA BITS: 8
PARITY: NO
STOP BITS: 1

These values are fixed and cannot be changed.
The node number can be changed by moving the mechanical switch to the desired number. Valid values are from 1 to 9. RS-485 units which are daisychained together must have unique node numbers. Zero is not a valid node number.

The Modbus Terminal Board must be configured prior to use. This typically requires the channels to be configured for the type of sensor to be used. Modbus registers 40067 – 40286 are responsible for configuring all the channel configurations and are stored in FLASH/EE memory and have a maximum of 100k write cycle endurance. These Modbus registers will retain their value even after a power down. Registers greater than 40769 are stored in RAM locations and may be written as many times as needed and are cleared (00h) after a power up condition.

In order to configure a channel for a particular type of input, 5 Modbus registers must first be configured according to section 9. Configuring the channels entails entering the numbers according to the chart. For example, to configure channel 12 for a 0-50 PSI transducer from a standard Altronic transducer, the following registers must be programmed:

40113 – 213
40114 – 5464
40115 – (-125)
40116 – 625
40268 – 1

This allows channel 12, registers 30023-30024, to display a swapped floating point for that particular channel.

When the input has been violated, this will cause the digital outputs to all turn off and the 4-20mA outputs to immediately go to a pre-configured state as defined by Modbus registers 40067 and 40068.

The sensor must be a linear signal in order for the displayed value to be read correctly. Many HMI/PLCs can ‘linearize’ the input signal.

To properly understand how to configure the channel, it is first necessary to know how the sensor relationship between voltage and displayed value (pressure, temperature, other) works.

Given the example in section 6.3, a standard 0 – 50 PSI sensor will be examined. For the Altronic style sensor, .5V will display 0.0 PSI and 4.5V will display 50.0 PSI. Refer to Voltage vs Pressure chart.

TROUBLESHOOTING

7.1 The power LED on the board is not illuminated

7.2 Neither the RX nor the TX lights are flashing

7.3 RX light is flashing, but the Modbus Terminal Board is not responding

MODBUS ADDRESS LIST

TRANSDUCER TABLE

DRAWINGS SECTION