Gasboy Gilbarco Interface Unit - Manual (Page 42)

34 Hardware Gilbarco Interface Unit v2.1
Gasboy CFN Series
Pin # Signal Name Description
P1-1 1 + Current loop sink
P1-2 1 - Current loop source
P2-1 2 + Current loop sink
P2-2 2 - Current loop source
Note that the signal names are confusing. The signal P1-1 + is negative, and the P1-2 - is positive.
Interface unit with firmware version 2.0 uses only P1. Some early beta versions also used P2, as
the CRIND interface loop. Released version 2.0 uses the spare RS485/422 port for CRIND
communication. The later firmware is compatible with the earlier, modified, units. These may
continue to use the second current loop port when they are upgraded, if switch DIP switch bank
3, position 3 is set to CLOSED.
Building a dual input mode distribution box
The dual input mode distribution box, with one input RS485/422 and one input current loop, is
not a standard Gilbarco offering, nor do their installation manuals show any diagrams of such.
However, it is easy to construct one of these, starting either with two distribution boxes, or with
one box and a kit.
If you have two dual distribution boxes, one set up for current loop input, one for RS485/422
input, you can construct two dual input mode distribution boxes by swapping two cables and
moving some jumpers.
You can also build a dual input mode distribution box from a single distribution box of either
the current loop or RS485/422 input variety, and one K93717 expansion kit. The K93717 kit
contains both input cables, a T17651 distribution box circuit board and some other cables.
The result in either case is the same, as illustrated in figure below. This is a dual RS485/422
input distribution box, except that the second input has been changed into a current loop input by
moving the jumpers JP10 and JP12, and by exchanging the second R19249-G1 cable plugged
into P103 for an R18810-G1 cable plugged into P102.