Sign in to follow this  
Followers 0
Guest KK

Df1 Half Duplex On Radio Modems

3 posts in this topic

I have configured a SLC5/04 as a DF1 Half Duplex Master polling a MicroLogix1000 slave. Using the option ""Half Duplex without Continuos Carrier" I tested it out using a direct cable, with RTS and CTS shorted together and it seems to work fine. I did a MSG Write and MSG Read. When I plug in the radio modems, something funny happened. The MicroLogix1000 seems to "see" the message Write from the Master and switched on some corresponding points as per my logic, but the master thinks that the slave is not responding. On further probing, I found that the reply from the slave to the master (I think it's "ACK" since the MicroLogix1000 did execute the logic correctly) did not get through. I found this out by testing each control line between the Master PLC and the radio modem. Has anyone come across similar situation before? I am using a TAIT T2000/2 Series II radio modem (1200/2400 bps)

Share this post


Link to post
Share on other sites
Most radio modems use the RTS/CTS lines to control the radio transmitter function. I am thinking that because your RTS/CTS lines are shorted together that the slave did answer with 'ACK', but the radio transmitter did not switch from receive to transmit. Try opening the short on the RTS and CTS lines. Connect RTS to RTS and CTS to CTS on the slave radio modem.

Share this post


Link to post
Share on other sites
Opps.. I only sorted the RTS/CTS when I was using the cable between the radios... When I connected it to the radio modems I connected the RTS and CTS lines. I have tried playing around with "RTS off delay" & "RTS send delay" times, ranging from 0, 10, 20, 50, 1000, 2000... but still no luck...

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0