METSOmaxPAC Hardware Reference Guide

 To attach the chassis assembly: 

1. At the desired chassis assembly mounting location in the cabinet, place 

eight 10-32 nut retainers (Metso Part No. 003530) in the rear mounting 

rail holes that correspond to the eight screw slots on the Model IOP 

chassis assembly. 

2. The holes in the maxDNA cabinet rear mounting rails are arranged in a 

repeating pattern of two holes close together separated by a single hole. 

To make sure all chassis assembly mounting screw cutouts line up to 

corresponding mounting rail holes, you must align the top mounting 

screw cutouts (left and right) of the chassis assembly with the top holes 

(left and right) of two hole pair. 

3. Position the chassis assembly (two ribbon connectors to the right) so that 

the screw slots align with the nut retainers. Insert eight 10-32 mounting 

screws (Metso Part No. 030162) and tighten securely. 

Cabling, power wiring, and chassis assembly to cabinet frame grounding 

should be completed before mounting the I/O modules. See next section. 

Cabling, Power, and Ground Wiring

This section describes power wiring, Model IOP I/O connection, and 

connection to other Model IOP I/O units. The connections covered in this 

section should be done after the chassis assemblies are in place and before 

the I/O modules are mounted. Some cabling can be done when the I/O 

modules are mounted, but the job is easier when they are removed. (See also 

Interconnecting I/O Racks). 

Cables used in the maxDNA Distributed Control Systems are labeled at both 

ends with the device and connector number. Interconnecting ribbon cables 

are designed for specific orientation, however, the connectors still prohibit 

wrong electrical connection. 

Refer to Publication 278561, System Power and Grounding, for a discussion 

of cabinet grounding. 

Supplying 24V Power to the I/O Modules

The I/O system requires a 24 Vdc ±4.0 Vdc power supply. Normally, this is a 

maxDNA power supply mounted in the cabinet holding the DPU; to ensure 

reliability, Metso Automation recommends using a maxDNA power supply 

exclusively. If another 24 Vdc power supply is used, it must meet the same 

specification requirements as the maxDNA supply. All modules are 

individually fused. The CMOS technology in the Model IOP I/O design 

results in low module power consumption. 

Whether the power source is the standard maxDNA supply or another 

supply, the +24 Volts connector plugs into the 24V connector on the right 

side of the I/O backplane. 

Caution: The +24 Vdc power supply used to power any maxDNA hardware 

should never be used for external relay contact wetting or to power any other 

field equipment. Use a separate supply for contact wetting to provide noise 

and interference protection for the maxDNA hardware. 

Interconnecting I/O Racks

Use a ribbon cable to interconnect, in a daisy chain manner, two or more 

adjacent I/O chassis assemblies in the same maxDNA I/O cabinet group. The 

cables should be installed in a manner that minimizes the total I/O bus length. 

This is done by utilizing the I/O bus connectors on both ends of the racks so 

that the bus “flows through” the racks. 

For example, consider the two-cabinet system shown in Figure 1-5a. A 

maxDPU4F pair is installed in the leftmost slots of the top two racks in 

cabinet 1. The bus begins at the DPU and flows through the rack to the 

connectors on the right side of the rack (P9 & P10). A ribbon cable connects 

the right side of rack 1 to the right side of rack 2. The bus flows through 

rack 2 to connector P11. Another ribbon cable connects the left side of rack 

2 to the left side of rack 3. The bus flows through rack 3 to connectors P9 

and P10. This same pattern is repeated until the last rack has been reached. 

Notice that the bottom rack of cabinet #1 is connected to the bottom rack of 

cabinet #2 by a cable that runs from P11 to P9. This is because that results in 

a shorter cable length than it would be had it run from P11 to P11. It is also a 

much shorter cable length than if it had been run from the bottom of cabinet 

1 to the top rack in cabinet 2. 

To reiterate, when cabling the I/O racks together, the goal is to keep the I/O 

bus length as short as possible. Connecting the cables on alternate sides of 

the racks so that the I/O bus “flows through” from one rack to the next does 

this. 

Note that the ribbon cable connectors are keyed. The color stripe on the 

ribbon cable should match pin 1 on the backpanel connector. Connector pin 

1 is indicated by a white triangle symbol on the backpanel adjacent to the 

connector. 

A bus terminator (CPO402) must be installed at the end of the I/O bus 

farthest from the DPU. The bus terminator is a small PC card assembly that 

is designed to plug in to the I/O bus connector. When installing a terminator, 

be sure to match its pin 1 indication to the pin 1 indication on the backpanel.