SLC5/03 - DF1 Radio Modem

Hi,

Can you communicate to a PLC on the RS-232 port (DF1) after changing the protocol from DF1 Full Duplex to DF1 Radio Modem using RSLinx?

I am trying to setup a radio network to allow me to see the site PLC's over radio. (MDS Transnet 900 for those radio guys) The link is strong on the radio's. I have 2 SLC5/03 that I want to put on the network but am having trouble wraping my head around full duplex, half duplex or radio modem mode. It sounds like radio modem mode is right, but half duplex would also work. Any insite? I do not have my PCMK card with me in the field so once I change the port, and am not able to communicate with the PLC I am dead in the water, so I just wanted to check with somebody who may have done what I am attempting.

Vic

I have always used DF1 Radio Modem with SLC-5/05 controllers where it was easy to use Ethernet to go online and monitor the controller. I don't recall if I could actually browse through the controller and out to the slave devices.

Ideally you'd have a -PCMK, -PIC, or -UIC, but you've got what you've got.

There is no DF1 Radio Modem driver in RSLinx Classic, so as you have ascertained once you have set the SLC-5/03 port for DF1 Radio Modem you're commited.

One way to handle this system would be to set up the SLC as a Half-Duplex Master in Standard (polling) mode and use the RSLinx Half Duplex slave driver. The SLC will poll your plugged-in computer and RSLinx can respond. Your computer node number has to be one of the polled slave devices.

This is especially helpful when you are in a remote station and need to plug into that slave radio to go online with the master or another slave. It's not fast, but it's faster than getting in the truck and driving to the remote station.

Thanks

Thanks for the reply.

Normally I have a PCMK card for my laptop to get on to the PLC, just for today was the issue. I tried to wing it and put the PLC in DF1 Half-Duplex Slave mode and now I cannot talk to the PLC. I will have to get the PCMK card and reset that port.

Is Radio Modem mode the right mode for the job? I am willing to give up the port if required to do the job right.

I think I am going to take a SLC home and play for a bit.

Vic

If the controller is set to DF1 Half Duplex Slave. Then use the DF1 Half Duplex Master in RsLinx, different node address.

Amazing what a night's sleep and some coffee can do. I badly mis-understood your question.

What I think you want is to have a central location from which RSLinx and RSLogix can communicate with your SLC controllers over serial radio modems.

Mickey is right on; set up the SLC controllers as DF1 Half Duplex slaves, and set up your RSLinx station as RSLinx DF1 Half Duplex Master.

I don't think you even need to set up a polling list in RSLinx just for RSLogix 500 use; it will send packets to the slave on demand.

If at all possible, do not use Hardware Handshaking because it is not well supported in XPSP3 or Vista. As far as I know it works in Windows 2000SP4 and XPSP2.

I setup a test PLC network in my home and here is what I have determined.
Using Halfduplex is too slow. I am using a 3rd party device to poll the PLC. I can set the retries up but then each tag takes over 3 seconds to poll and with over 90 tags to poll it doesn't work.
So I tried the Radio Modem mode and after some trial and error it works perfectly for the task. I had to use the full duplex DF1 driver.
I can also communicate to address 1 SLC with RSLinx, but cannot see any other SLC's on the network in RSLinx, but the 3rd party device can see all the devices on the network.

I am currently downloading RSLINX 2.56 and will contiunue to try to get the radio modem to talk back to RSLinx on other addresses than 1. (not required, but would be nice)

I am confused again. I thought you described wishing to have RSLinx communicate with both controllers via radio. What is the third-party device and how does it fit into the picture ? Do you want both RSLinx and the third party device to have access to the SLCs simultaneously ?

3 seconds to poll a tag is an eternity. There must be something wrong in the configuration or the radios. Even with the slowest baud rate and slowest handshaking methods, I've never seen a functional radio link take more than 250 milliseconds to poll a single register over DF1.

DF1 Full Duplex and DF1 Radio Modem are, as you have discovered, similar. But DF1 Full Duplex is a point-to-point protocol and you're not going to get it to work like a multipoint protocol.

The third party device is a Matrix PAC which is a device that converts a lot of field devices into a common protocol simular to modbus.
The PAC talks DF1, ROC for Floboss RTU's, ScanCom for the barton scanners, Modbus for most devices, ect and can communicate back to our host via Sat modem, cell or ethernet. The people who sell the PAC told me that no one had ever used the PAC to do what I have done with it. I compared the PAC to RSLINX to help people understand the concept I was trying to achieve. It would be nice to unplugg the PAC and pluc a laptop into the radio to communicate with RSLINX, but I was getting too hung up on it. RSLinx worked fine at half duplex but the PAC was having an issue. So through trial and error I have determined the PAC's DF1 Full Duplex is an addressable protocol and allows me to use DF1 Modem driver in a multidrop scenario, but cannot use RSLINX to talk to PLC's.

Sorry for any confusion, but I was very confused when I started on this project and was trying to get as much info as I could to point me down any path.

Thank you very much for your help.