VMP2
Configuration
ID 24855, Rev. 02
Page 4 - 4
© 2002 PEP Modular Computers GmbH
4.1.3
Resistor Setting for Non-standard Socket Devices
The default pinout of this socket is designed for use with standard DIL Flashes and M-
Systems DiskOnChip. As some devices have a different pinout, resistors must be set
accordingly (please see figure 2-4 for an illustration of these resistors on the board)
Note: All resistors are 0 ohm
4.1.4
RS485 Termination (Onboard Interface Only)
When the VMP2 is using the onboard RS485 interface and is the last on the RS485 bus,
then the RS485 interface must provide termination resistance. The purpose of J3 is to
enable this line termination resistor (130 R).
Additionally, the correct idle line potential must be provided at one location within the
RS485 bus. J4 and J5 are used for this purpose. Pullup/Pulldown resistors are 380 Ohm
each.
Table 4-2: Resistor Setting for Various Non-standard Socket Devices
Used Socket Devices
R3
R6
R7
R8
R11
R12
R13
Flash (default)
Open
Open
Open
Set
Set
Open
Set
DiskOnChip (default)
Open
Open
Open
Set
Set
Open
Set
NVSRAM
Open
Open
Set
Open
Set
Set
Open
4 Mbit EPROM
Set
Set
Open
Open
Open
Open
Set
Table 4-3: Jumper Settings for RS485 Termination
Termination
J3
ON
Set
OFF
Open
Note:
Ensure that the reference potential for the RS485 signals are set
in one location only on the bus.
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