EATON MTL4850 HART multiplexer complete guide

For hazardous area applications that require intrinsic safety explosion-proof, MTL provides backplates that can be used in conjunction with MTL4500 series isolators.

2.3.1 CPH-SC16 (R) and CPH-SC32 (R) Backboards

These backboards are designed specifically for MTL4500 series analog input/output modules, capable of accommodating 16 MTL4500 modules (CPH-SC16) or 32 MTL4500 modules (CPH-SC32), and each board carries one MTL4850 module.

CPH-SC16: It is mainly used in conjunction with MTL4541/MTL4451A (single channel analog input) and MTL4546 (analog output).

CPH-SC16R: Pre install a 250 Ω resistor on the control system terminal to provide 1-5V signal to the host, only MTL4541/MTL4451A module can be used.

CPH-SC32: It is mainly used in conjunction with MTL4544/MTL4544A (dual channel analog input) and MTL4549/MTL4549C (analog output).

CPH-SC32R: Pre install a 250 Ω resistor on the control system terminal, only MTL4544 module can be used.

Connection and Expansion:

Two CPH-SC16 (R) backboards can be cascaded with 34 flat cables through P1/P2 connectors to utilize the 32 channel capacity of MTL4850. Only the backplane with MTL4850 needs to be connected to an RS485 link.

All backboards provide two RS485 ports for cascading.

Provide redundant 24V DC power input, LED indication, with 0.5A fuse protection. The maximum current of CPH-SC16 (R) is 0.65A @ 24V DC, and the maximum current of CPH-SC32 (R) is 1.2A @ 24V DC.

Address setting: Set the HART address of MTL4850 through the 6-digit DIP switch (SW1) on the board.

2.4 Installing Accessories

MTL provides a variety of installation accessories to facilitate the installation and labeling of backboards:

Surface mounting kit (SMS01): used to install the backplate on the panel, including M4 x 20mm screws, locking washers, flat washers, 10mm spacer columns, and washers.

DIN Rail Installation Kit (DMK01/DMK04): Used to install the backplate on a DIN rail, including mounting screws, locking washers, flat washers, spacer posts, washers, and mounting feet.

Tag Strip Kit (TSK18): Used to install tag strips above the backplane secure area connection for easy channel identification.

Grounding Rail Kit (ERK18): Used to connect hazardous area cable shielding layers or spare wire pairs, installed on the back panel at the same height as the top of the module.

Safety information and installation precautions

3.1 General safety precautions

Hazardous area restrictions: Equipment must not be installed in hazardous areas unless it is certified and marked for use in hazardous areas or protected by locally recognized explosion-proof technology.

Comply with local regulations: Ensure that all installation work complies with local standards, operating procedures, and on-site regulations.

Intrinsic safety system verification: Check whether the equipment in hazardous areas complies with the descriptive system documents. If you have any questions, please refer to the certificate or contact MTL for confirmation.

Functional correctness: Check whether the functionality of the interface unit is suitable for the application scenario.

3.2 Precautions for Maintenance of Intrinsic Safety Isolator Modules

Most operating procedures allow for live maintenance while maintaining the integrity of intrinsically safe equipment or systems. When maintaining the MTL4500 module with electricity, it is necessary to plug and unplug the hazardous area connector on the top of the module, so the cables on the connector should have a certain degree of flexibility for operation.

After unplugging the hazardous area connector, care must be taken not to place it in a position that may come into contact with the backplane or backplane components. The backplane is connected to the safe zone circuit, therefore it is not intrinsically safe. Unprotected connectors may disrupt the necessary isolation between safe and hazardous area circuits. This can be avoided through the following methods:

Immediately insert the connector into the MTL4599 virtual isolator or other uninstalled MTL4500 module after unplugging (but do not insert any other modules already installed on the backplane).

Provide a method for temporarily fixing connectors to prevent them from contacting the backplane or safe zone circuits.

3.3 Post installation inspection

It is recommended to regularly (at least once every two years, and more frequently in harsh environments) check the installation condition:

Is the module type correct and installed in the correct position on the backplane.

Whether the labels of the module and hazardous area connectors are correct and clear, whether the connectors are inserted into matching modules, and whether the label information is consistent with the document.

Are the modules and hazardous area connectors securely inserted.

Is the connection between all backboards and hazardous area connectors correct and reliable.

Whether the cable type and rating are correct, whether the wiring is reasonable, and whether there is wear or damage.

Is the cable shielding layer properly grounded.

Electrical connection

4.1 Power Connection

HTP-SC32/HMP-HM64: Connect redundant 24V DC power supply through 4-position pluggable screw terminals. The terminal allocation is shown in Figure 4.3. The LED indicates the power status.