© National Instruments Corp. 5 FP-CTR-502 and cFP-CTR-502
Inputs
Each input channel has one input terminal, VIN. Each channel also
has VSUP and COM terminals that can supply power to field
devices or provide additional connections to the external power
supply. You can connect the eight count-input channels and four
gate-input channels to devices with sinking outputs. The
[c]FP-CTR-502 has sourcing inputs, which means that the VIN
terminal provides a path to a voltage supply.
The [c]FP-CTR-502 input channels are optically isolated from
therest of the FieldPoint bank and have current-limiting circuitry.
All the input channels are referenced to the V and VSUP terminals.
In the ON state, an optoisolator is turned on between the positive
external supply voltage (V and VSUP) and the input (VIN).
When choosing your external devices and power supply, keep in
mind that the input-logic thresholds are defined by the power
supply as detailed in the Specifications section.
Vthreshold = VSUP – VK
where Vthreshold is the threshold voltage for the channel
VSUP is the supply voltage, measured across VSUP
andCOM
VK has a value of 2–3V
When VIN, the voltage across VIN and COM, is lower than Vthreshold,
the channel is ON. Therefore, if you connect a 24V power supply
to the [c]FP-CTR-502, an input channel registers an ON state when
Outputs
Output 0 13 29 30
Output 1 14 29 30
Output 2 15 31 32
Output 3 16 31 32
1 Install a 1 A maximum, fast-acting fuse on each VOUT terminal.
2 Install a 2 A maximum, fast-acting fuse on each V and VSUP terminal.
Table 1. Terminal Assignments (Continued)
Channel Name
Termi na l Nu mb ers
VIN or VOUT1VSUP2COM