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VP-8IP / Sep 2013
G E N E R A L I N F O R M A T I O N
General Purpose Interface (GPI/GPO)
The VP-8
iP
is equipped with eight General Purpose Input (GPI) control input
ports on one female DB-9 connector, and four General Purpose Output (GPO)
tally outputs on a second female DB-9 connector. All GPI and GPO connections
are optically-isolated to prevent external ground loops and prevent dangerous
voltages from being introduced into the VP-8
iP
.
GPI
The GPI interface provides eight separate General Purpose Inputs, sharing a
common return. The connector is a female DB-9 connector with the following
pin assignments. Note that all pins are isolated from VP-8
iP
internal circuitry!
Pin 1 – GPI COM (-)
Pin 6 – GPI 1 IN (+)
Pin 2 – GPI 2 IN (+)
Pin 7 – GPI 3 IN (+)
Pin 3 – GPI 4 IN (+)
Pin 8 – GPI 5 IN (+)
Pin 4 – GPI 6 IN (+)
Pin 9 – GPI 7 IN (+)
Pin 5 – GPI 8 IN (+)
The GPI input circuits are optoisolated by devices with a 1,500VAC isolation
rating.
Each of the GPI inputs is current limited by a 475 ohm resistance. The LED
device inside the optoisolators is rated at a maximum forward current of 50mA
with a normal operating current of 5mA; therefore it is necessary to determine
if an additional outboard series resistance will be required in your particular
application.
The following table lists the value of external resistance required when the
external voltage applied to the GPI exceeds 3.3VDC. In all applications up to
and including 48VDC, a one-half watt resistor is sufficient.
Applied Voltage to GPI External Resistance
3.3 VDC
None
5.0 VDC
330 Ohms
6.0 VDC
470 Ohms
7.5 VDC
820 Ohms
10 VDC
1.3 kOhms
12 VDC
1.8 kOhms
15 VDC
2.4 kOhms
24 VDC
3.9 kOhms
30 VDC
5.1 kOhms
48 VDC
9.1 kOhms
