I have a VM140 board that I connect to a k6714-16 relays card.
I connect the 8 analog and 8 numeric outputs (VM140) to the 16 relays (K6714-16).
For the analog outputs, I connect ground (VM140) to ground (K6714-16) and outputs 1-8 (VM140) to inputs 1-8 (K6714-16). Everything works fine, the relays can be commuted.
For the numeric outputs, I connect ground (VM140) to ground (K6714-16), clamp (VM140) to VB (K6714-16) and outputs 1-8 (VM140) to inputs 9-16 (K6714-16) . If i want to switch one relay it doesn’t work. The output led of the VM140 is lighted but the corresponding relay doesn’t switch.
What should I do?
The digital outputs of the VM140 are open collector outputs.
In the K6714-16 manual is written:
“[color=#008000]The ULN2803 type transistor array allows you to control the relays direct from a TTL or CMOS. For controlling the relay with open collector control, don’t mount the transistors arrays.[/color]
[color=#008000]ATTENTION : In case you don’t use a transistor array (IC’s for K6714-16), fit he wire jumpers in the places for IC1 and IC2, marked with a dotted line.[/color]”
You have to remove the ULN2803 (IC1 or IC2) connected to the digital outputs of the VM140.
Replace the removed ULN2803 with 8 jumper wires as illustrated in the K6714-16 manual.