User`s manual

XP840038 s Software Reference

Relay Board Addresses

Physical Addresses

Up to 64 addresses are possible on a single PLCBus. The 12-bit address

of a particular relay board is determined by two factors: (1) the encoding

of the PAL chip installed on the board, and (2) jumper settings on header

J1. Since eight different PALs are available and J1 can be set eight

different ways, 64 unique addresses are possible.

A 12-bit address can be conveniently placed on the bus using 4-bit

addressing. A 12-bit physical address has the following format:

000z000ypppx

Jumper bits are defined by the following pin settings:

z = 1 when J1 pins 56 are not connected

y = 1 when J1 pins 34 are not connected

x = 1 when J1 pins 12 are not connected

and

ppp is determined by the PAL.

The physical addresses correspond to the following PLCBus addresses.

000zBUSADR0

000yBUSADR1

pqrxBUSADR2

Logical Addresses

PLCBus expansion boards have logical addresses. Relay-specific

software defines 64 integer board addresses, 063. The formula mapping

physical address to logical address is defined by the following equation:

logical address = pqr × 8 + zyx

The PAL encoding (pqr) and jumper bits (z, y, x) are defined above.

For example, a relay board that has PAL FPO4550 (pqr = 101) and J1 pins

5 and 6 connected (zyx = 011) would have the following addresses.

physical address: 000z000ypqrx = 000000011011 = 0x01B.

logical address: 101

× 8 + 011

= 43 = 0x2B.

Certain library functions expect a logical relay address.