7 Segment display

[Guest Jefftoh]

Hi, I need to complete a display project for demostration. The PLC is using A series PLC, and I have to drive 8 7-segment to simulate a fill up process. I know I can use the 7-segment decode function inside the PLC, is it possible I can using scanning method to reduce my IO points and wiring job? Will the PLC procesing time and physical output ON/OFF time can achive? Looking forward for your advices. Thanks and have a nice day.

[panic mode 246]

yes but t multiplex you will need to use two output cards - one sinking and one sourcing. Another way is to use solid state relays and just one card. For example, if you have common cathode 7-seg displays, you could use sourcing output card as follows (just an example): Y0 - a Y1 - b Y2 - c Y3 - d Y4 - e Y5 - f Y6 - g Y7 - dp Y8 - CR1 Y9 - CR2 YA - CR3 YB - CR4 YC - CR5 YD - CR6 YE - CR7 YF - CR8 Wire contact of CR1 between DISP1 cathode and 0VDC, CR2 with DISP2 etc. The output card MUST be transistor type. You cannot use Relay outputs because they are way to slow for the application. In case your output card is sink type or the displays use common anode, you have to make some changes of course. Since standard LED displays usually do not have built in resistors and assuming you use 24VDC to run them, please insert resistors between PLC outputs and segments (a-g and dp). For 24VDC operation and 18mA current for each segment, you would need 1.2kOhm resistors 1/2watt. Have fun