Spectrum Controls 1756sc-CTR8 - Manual (Page 13)

Chapter 1: Module Overview
3
System Operation
At power-up, the module checks internal circuits, memory, and basic
functions. During this time the SYS LED remains on. If the module does
not find any faults, it turns off the SYS LED.
After completing power-up checks, the module wait for a connection to an
owner controller then valid channel configuration data from your ladder
logic program. After channel configuration data is transferred, and one or
more channels are enabled, the module continuously converts the inputs to
floating point data for use in your ladder program.
Each time the module reads an input channel, the module tests that data
for a fault, i.e. signal mismatch, or out of range condition. If it detects an
error condition, the module sets a unique bit in the status tags.
Module Operation
The module’s input circuitry consists of eight single-ended inputs, routed
into an FPGA. The FPGA reads the input signals and converts them to
counter and rate and then presents them in floating point values.. The
input circuitry also supports gate inputs allowing you to disable and control
counter operation.
Cables
Cable length should be kept to a minimum. Use the lowest capacitance
shielded cable available. We recommend that you use Belden #9501 (or
equivalent).
Table 1.2 Cable Specifications
Description Belden #9501
When used? AC/DC inputs.
Conductors 2, #24 AWG tinned copper (7x32)
Shield Beldfoil aluminum polyester shield w/ copper drain wire. .
Insulation PVC
Jacket Chrome PVC
Agency NEC Type CM
Approval
Temperature 80°C
Rating