Maple Systems HMC7000 Series - Manual (Page 73)

HMC7000 Series I/O Module Guide
Phone: 425/745-3229 • Fax: 425/745-3429 • Email: [email protected] • www.maplesystems.com .
1010-1043 Page 72 of 85 Rev. 02, 11/08/2013
Note: arrow indicates current flow direction
In order to have current flow, each I/O terminal on the expansion module must have a return path
or a signal ground connection. In most modules, multiple I/O terminals share the signal ground
connection.
Digital Outputs (PNP or NPN type)
The output terminals of a digital I/O module use an optically isolated PNP or NPN transistor to
energize the connected load. PNP/NPN outputs are faster than relay outputs but can only work
with low current DC loads (typically 500mA max per terminal). PNP modules are sourcing
modules, and NPN modules are sinking modules.
PNP-type connection (Source) NPN-type connection (Sink)
Note: the above diagrams show that a PNP output is ‘sourcing’ current and the NPN output is
‘sinking’ current.