Connect Tech CTIM-00043 Performance Enhancement , CAN Bus Options , Interrupt Mode and Selections

CANpro/104 User Manual

CTIM-00043 (0.01) 1/15/2010 www.connecttech.com 14

800-426-8979 | 519-836-1291

Performance Enhancement

PC/104 Memory and I/O Bus cycles are typically about 700 nS long in total, but the access speed of the

SJA1000 is considerably faster. The PC/104 Bus allows Memory and I/O Bus cycles to be shortened by the

assertion of the SRDY* signal at the appropriate time in the Bus Cycle. This shortening of the PC/104 Bus

Cycle can yield some significant performance improvements is some applications.

The CTI CANpro/104 board allows the PC/104 Bus cycle to be shortened by about 30% with Jumper J3C

Position #6.

J3C Position #6

Function

Removed

Normal PC/104 Bus Cycle length

Installed

Shortened PC/104 Bus Cycle length

Table 14

Note: Not all System boards will support Bus Cycle shortening via the PC/104 SRDY* signal.

Consult with the manufacturer of your System board to determine if this feature is supported.

CAN Bus Options

The board supports 2 CAN Bus Options with Jumper J4 and J5.

J4 is associated with CAN Port-0, and J5 is for CAN Port-1.

CAN Bus Termination

Ground the Shell of the 9D Connector

A 120 ohm termination resistor is placed across the CAN Bus signals (CANH and CANL), by

placing a jumper on Position “T” of either J4 or J5. It is desirable to place a termination resistor at

each physical end on a CAN Bus segment.

On CANpro/104 boards equipped with a 9D CAN Bus connector, the Metal Shell of that connector

can be connected to the Isolated Ground of the board (each CAN Port has a separate Ground), by

placing a jumper on Position “G” of either J4 or J5. This might be useful in some installations to

reduce noise.

Interrupt Mode and Selections

The board can be operated with either one or two interrupts, the interrupt(s) can be shared with another

PC/104 board (which supports shared interrupts), and the Pull-down resistor, which is required for shared

interrupts, can be enabled on this board.

The Jumper Blocks consist of 2 groups of Interrupt Selections, one group for the CAN-0 controller (red box)

and the other for the CAN-1 controller (blue box).