Delta Tau PMAC2A-PC/104 Instrukcja Obsługi Pobierz pdf (Strona 13)

PMAC2A-PC104 Hardware Manual

Baseboard Hardware Setup 7

Resistor Packs Configuration

Differential or Single-Ended Encoder Selection

The differential input signal pairs to the PMAC have user-configurable pull-up/pull-down resistor

networks to permit the acceptance of either single-ended or differential signals in one setting, or the

detection of lost differential signals in another setting.

The ‘+’ inputs of each differential pair each have a hard-wired 1 kΩ pull-up resistor to +5V. This cannot

be changed.

The ‘-‘ inputs of each differential pair each have a hard-wired 2.2 kΩ resistor to +5V; each also has

another 2.2 kΩ resistor as part of a socketed resistor pack that can be configured as a pull-up resistor to

+5V, or a pull-down resistor to GND.

If this socketed resistor is configured as a pull-down resistor (the default configuration), the combination

of pull-up and pull-down resistors on this line acts as a voltage divider, holding the line at +2.5V in the

absence of an external signal. This configuration is required for single-ended inputs using the ‘+’ lines

alone; it is desirable for unconnected inputs to prevent the pick-up of spurious noise; it is permissible for

differential line-driver inputs.

If this socketed resistor is configured as a pull-up resistor (by reversing the SIP pack in the socket), the

two parallel 2.2 kΩ resistors act as a single 1.1 kΩ pull-up resistor, holding the line at +5V in the absence

of an external signal. This configuration is required if complementary open-collector drivers are used; it

is permissible for differential line-driver inputs.

If Pin 1 of the resistor pack, marked by a dot on the pack, matches Pin 1 of the socket, labeled by a white

square, then the pack is configured as a bank of pull-down resistors. If the pack is reversed in the socket,

it is configured as a bank of pull-up resistors.

The following table lists the pull-up/pull-down resistor pack for each input device:

Device

Resistor

Pack

Pack Size

Encoder 1 RP30 6-pin

Encoder 2 RP31 6-pin

Encoder 3 RP36 6-pin

Encoder 4 RP37 6-pin

1 2 ... 8 9 10 11 12 13 14 15 16 17 18 ... 71 72

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