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Hardware Build - Without the REB PCB

Building a Rose Engine Butler: 1. Parts · 2. Common build steps · 3a. With the REB PCB · 3b. Without the PCB · 4. Software

This page is for building the boxes without the REB circuit board. Each Mesa 7i92TH card's 26-pin headers are brought out to IDC26 breakout boards (26 screw terminals on a DIN rail) with IDC26 ribbon cables, and everything else is wired to those terminals.

The software is exactly the same as for a machine built with the REB PCB: it only knows the card's pins, so the wiring below must match it.

Before starting:

• Get the parts marked Both and Without PCB on Hardware Parts.
• Do the common build steps (DM542T switches, Mesa jumpers, network and power).

Terminal numbers below are the card's 26-pin header pin numbers, which match the breakout board's terminal numbers when the ribbon cable is fitted the right way round (the red stripe on pin 1 at both ends). Mesa's pin file (7i92t_REB.pin) numbers the same pins differently, as a 25-pin plug would - don't wire from it. The full map is on Mesa 7i92TH Pin Mapping.

Power Connections

Network Connections

Base Box

Two breakout boards: one on the card's P2 header and one on P1.

Stepper motor drivers (channels 00 - 05)

Limit jacks, E-stop button and signal tower

Other terminals

• GND: P2 terminals 10, 12, 14, 16, 18, 20, 22, 24; P1 terminals 10, 12, 14, 16.
• 5 V: P1 terminals 18, 20, 22, 24 (with the card's W3 jumper up). Never connect these to a GND terminal or to the 24 V supply. Whether they can power the three relay modules is To be confirmed.
• Leave unconnected: P1 terminals 9, 11, 15, 17, 19, 23 (they drove channels 06 and 07 on the earlier 8-channel boxes) and terminal 26 on each header.
• Spare inputs: P2 terminal 21; P1 terminals 3, 7.

Expansion Box

One breakout board, on the expansion card's P2 header. Its P1 header isn't used.

Stepper motor drivers (channels 06 - 09)

Limit jacks

Other terminals

• GND: P2 terminals 10, 12, 14, 16, 18, 20, 22, 24.
• Leave unconnected: terminal 25 and terminal 26.
• Spare input: terminal 21.

Connecting a DM542T driver

Each driver has three signal pairs. Set its 5V/24V switch to 5V first (see common steps).

On the P1 board, terminals 18, 20, 22 and 24 are 5 V, not GND - never connect the drivers' - terminals to them.

Limit switches and E-stop button

• Wire a normally closed switch between its terminal and a GND terminal. The card's pull-up makes an open switch (tripped, broken or unplugged) read as tripped. No other parts are needed.
• Limit switch jacks are GX-12/2, the E-stop button jack is GX-16/2. See the User Manual's Limit Switch Cabling and E-Stop Button Cabling (↗ User Manual).

Signal tower

A breakout board has no relays, so three separate single-relay modules (part 1260) switch the tower: Relay Module 1 the red light, Relay Module 2 the green light and Relay Module 3 the siren.

Signal Tower Relay Connections

Each module is wired the same way:

• Two separate grounds: the modules' 5 V side (VCC, IN, GND) uses the Mesa card's ground, as above. The tower's 24 V side does not: the tower's common wire goes to the GND of the 24 VDC power supply, never to a breakout board terminal.
• Each module must switch on when its input is pulled low (a "low-level trigger" module). The card holds its pins high whenever LinuxCNC isn't running, so a high-level module would turn the tower on at start-up and after shut-down.
• See also Signal Tower Relays.

Next: Software Installation and Setup