J.P. Instruments EDM 740 Pilots Guide - Manual (Page 63)

For Your Safe Flight Page 63
Section 18 - EDM-851 TWIN ENGINE ADDENDUM
The following provides instructions for install / operation of the EDM-851 Twin
Engine configuration. Each EDM-830 instrument is installed to its respective engine
as if it were a single. One EDM operates as a ‘Master’, and the other operates as a
‘Slave’. This allows each instruments fuel computer values, such as total fuel
remaining, total fuel used, hours of endurance and so on, to be combined and
displayed on the Master.
The main differences for the twin installation (versus a single) are:
1. An interconnect cable (JPI PN 700725) is installed between the two
instruments, allowing them to cross-communicate. See ‘Illustration A’ below.
2. The right engine EDM acts as a ‘Slave’ unit and certain connections must be
made as follows:
a. If you do have the fuel flow option, install the supplied P4 harness (JPI
PN 700709-4) to the ‘Slave’ EDM. Install the other P4 harness (JPI PN
700709 no dash number) to the ‘Master’ EDM. Note: EDM <-> GPS
connections are only made between the GPS radio and the ‘Master’
EDM. None are made to the ‘Slave’ EDM.
b. If you do not have the fuel flow option, install the supplied P4 plug (JPI
PN 700709-5) to the ‘Slave’ EDM.
The following are reminders regarding installation requirements that must be
followed:
- Each EDM unit shall be powered by a dedicated circuit breaker.
- Each EDM unit shall be grounded directly to the engine that it is monitoring
(not the aircraft ground bus).
- Pilot Programming Mode and Factory Limits Mode should be performed on
each EDM unit to match them to the installation requirements. NOTE: these
parameters are intentionally not synchronized between the units. You must
program BOTH EDM’s.