testing dry contact (voltage free contact) in a frequecy of 10herts

[Anniyan_x]

HI there

currently i have input card, the configuration is as attached image View attachment 63917, i can connect drycontact based sensor/switch to it. basically a channel is activated when the channel is short to ground/common.. but now i need test the channel contact response by giving a 100ms voltless pulse(dry contact) meaning i need to short the common&DI channel for 100ms and check if the card can detect or not. im now not sure how to physical short it for 100ms, what type equipment i need to use, i have a pulse generator but that give a voltage based pulse, i do have a scope to.. but how to test dry contact...anybody have some ideas or any equipment that usualy can be used for this type of input testing.

wt rgds
anniyan

 

[ccurtis]

Why not use your pulse generator to drive a small relay and use the contacts of the relay? Alternatively, you could use a transistor to act as a switch instead of a relay, but your tester is for testing contacts. Best to go with the real thing. No? You never know if contact bounce is an issue unless you use real contacts.

A relay like this can be driven directly by test equipment pulse generators and has a built in diode to protect the generator. P/N 7103-05-1001 https://www.electro-tech-online.com/custompdfs/2012/05/7000_Series.pdf

Set your generator output level to 2.5V because this relay has a coil resistance of 100 ohms, whereas the voltage output of the pulse generator is referenced to a 50 ohm load. Or, use a scope to set the output voltage to 5V with the relay connected. Connect the relay coil across the output of the generator and the relay contact in place of a "field device".

 

[Anniyan_x]

OK... i'l follow this method, i guess il use both methods transistor/relay just for experimental purpose. i need now whats the minimum 'short-time' the card can detect input/ and also the contact bounce issue. thank u.