User Manual

TMCM-1240 Hardware Manual • Hardware Version V1.20 | Document Revision V1.20 • 2019-MAY-24

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3 Mechanical and Electrical Interfacing

3.1 Size of board

The board with the controller/driver electronics has an overall size of 37mm x 37mm x 11mm without

mating connectors. Maximum component height (height above PCB level) without mating connectors

is around 7mm above PCB level and 2.5 mm below PCB level. There are two mounting holes (3.2mm

diameter) for M3 screws for mounting to a NEMA17 stepper motor.

(0/0)

(21.5/1.75)

(35.25/22)

(1.75/12)

(8.5/35.25)

(37/37)

(3/34)

(34/3)

3.2

Figure 1: Board dimensions, position of mounting holes and position (pin 1) of connectors (all values in mm)

3.2 Board mounting considerations

The TMCM-1240 oﬀers two metal plated mounting holes. Both mounting holes are connected to system

and signal ground (same as power supply ground). In order to minimize distortion of signals and radiation

of HF signals (improve EMC compatibility) especially in sensitive / noisy environments it is important to

ensure a solid ground connection within the system. In order to support this, it is recommended to

connect both mounting holes of the board in addition to the supply ground connection to system power

supply ground. Nevertheless, this might not always be an option e.g. in case the metal system chassis /

TMCM-1240 mounting plate is already connected to earth and a direct connection between supply ground

(secondary side) and mains supply earth (primary side) is not desired / not an option. In this case plastic

(e.g. made of nylon) spacers / distance bolts and screws should be used.

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