15
HMC7000 Series Installation Guide
1010-1042 Rev 00
www.maplesystems.com
power supply and a field device (either some type of device that acts as a switch for inputs or a load in the case of an
output).
For a source connection, the current flows out of the expansion module’s input/output contact and into the common
(signal ground) contact. In other words, the I/O contact on the expansion module ‘sources’ or provides the current to the
switch contact or load.
A sink connection causes the current to flow into the expansion module’s input/output contact and out of the common
contact on the I/O module. In other words, the I/O contact ‘sinks’ or takes in the current from the switch contact or load:
Note: arrow indicates current flow direction
In order to have current flow, each I/O contact on the expansion module must have a return path or a signal ground
connection. In most modules, the signal ground connection is shared by multiple I/O contacts, hence the name ‘common’.
Each I/O contact is labeled for easy identification on the modules. As we mentioned above, ‘COM’ is the common
ground contact. A contact with an ‘X’ followed by a number is an input contact and a contact with a ‘Y’ followed by a
number is an output contact. The number refers to the position associated with each contact in the I/O module.
When you create your application project in MAPware-7000, you will have to assign a bit/register memory address for
each contact on the expansion module. MAPware-7000 provides you with the option to allow the software to do this
automatically. In this case, it will assign memory addresses according to the position and expansion slot in which the I/O
module is located.
In addition, many of the I/O modules have a three-pin connector that is used to connect a voltage source (usually
+24VDC). This voltage source drives the output contacts of the I/O modules.
Digital Outputs (PNP or NPN type)
The output contacts of a digital I/O module use an optically isolated PNP or NPN transistor internally to open/close the
connected load to the attached 24VDC power source. PNP/NPN outputs are faster than relay outputs but can only work
with low current DC loads (typically 500mA max per contact). In a PNP-type contact, the load end not connected to the
output contact is connected to the common (V-) terminal of the voltage source. A NPN-type contact has the load end
connected to the positive (V+) terminal of the voltage source: