User's Manual

PMAC2A PC104 Hardware Reference Manual
Hardware Setup
6
CPU Configuration Jumpers
E15A-E15C: Flash Memory Bank Select Jumpers – The flash-memory IC in location U10 on the
PMAC2A PC/104 base board has the capacity for eight separate banks of firmware, only one of which
can be used at any given time. The eight combinations of settings for jumpers E15A, E15B, and E15C
select which bank of the flash memory is used. In the factory production process, firmware is loaded only
into Bank 0, which is selected by having all of these jumpers OFF.
E10-E12: Power-Up State Jumpers – Jumper E10 must be OFF, jumper E11 must be ON, and jumper
E12 must be ON, in order for the CPU to copy the firmware from flash memory into active RAM on power-
up/reset. This is necessary for normal operation of the card. (Other settings are for factory use only.)
E14: Watchdog Timer Jumper – Jumper E14 must be OFF for the watchdog timer to operate. This is a
very important safety feature, so it is vital that this jumper be OFF for normal operation. E14 should only
be put ON to debug problems with the watchdog timer circuit.
W1: Flash chip select – Jumper W1 in position 1-2 selects a 28F320J3A part for the U10 flash chip.
Jumper W1 in position 2-3 selects a 28F320J5A part for the U10 flash chip. This jumper is installed in
the factory and must not be changed from its default state.
Communication Jumpers
E18-E19: PC/104 Bus Base Address Control – Jumpers E18 and E19 on the PMAC2A PC/104 CPU
determine the base address of the card in the I/O space of the host PC. Together, they specify four
consecutive addresses on the bus where the card can be found. The jumpers form the base address in the
following fashion:
E18 E19 Address (hex) Address (dec.)
OFF OFF $200 512
OFF ON $210 528
ON OFF $220 544
ON ON $230 560
The default base address is 528 ($210) formed with jumper E18 removed and E19 installed. This setting
is necessary when using the USB or Ethernet ports of the Acc-2P communications board.
ADC Configuration Jumpers
E16: ADC Enable Jumper – Install E16 to enable the analog-to-digital converter circuitry ordered
through Option-12. Remove this jumper to disable this option, which might be necessary to control
motor 1 through a digital amplifier with current feedback.
Encoder Configuration Jumpers
E20-E23: Encoder Single Ended/Differential Select – PMAC has differential line receivers for each
encoder channel, but can accept either single-ended (one signal line per channel) or differential (two
signal lines, main and complementary, per channel). A jumper for each encoder permits customized
configurations, as described below.
Single-Ended Encoders
With the jumper for an encoder set for single-ended, the differential input lines for that encoder are tied to
2.5V; the single signal line for each channel is then compared to this reference as it changes between 0
and 5V.
When using single-ended TTL-level digital encoders, the differential line input should be left open, not
grounded or tied high; this is required for The PMAC differential line receivers to work properly.
Differential Encoders
Differential encoder signals can enhance noise immunity by providing common-mode noise rejection.
Modern design standards virtually mandate their use for industrial systems, especially in the presence of
PWM power amplifiers, which generate a great deal of electromagnetic interference.