RedLion DSPLE and SLC 5/05

I Have an SLC 5/05 in the office configured as a Modbus RTU Master reading and writing data quite happily to and from 2 weight dosing terminals. My client wants me to go to site and try to get this to work with their existing equipment. I tried this before but we only had a short window and production demands meant we had to abandon our trial before we had it all working properly. I'm due to return to site to try again but they want me to take an alternative solution in case it doesn't work this time and we're planning to use a RedLion DSPLE as a gateway between the CPU and the Modbus devices.

I've watched a number of videos on how to use Crimson 3.0 but none are for exactly what I'm looking to do with it. I wondered if anyone in here has used the RedLion DSPLE with the SLC 5/05 and Modbus RTU?

Any tips or pointers would be greatly appreciated.

This is a pretty ordinary Data Block application, where you define "Red Lion to Device" blocks and "Device to Red Lion" blocks and configure them to move data from one to the other.

Are the Modbus devices on separate serial channels, or on one multidrop channel (generally RS-485) ?

How many blocks of Modbus data, of what type, are you reading from the weight dosing terminals ?

Do you also have to write Modbus data to the weight dosing terminals ?

I happen to have a DSPSX and an SLC-5/05 in my test bench supplies.

Hi Ken and thanks for your reply.

I have had the set up working with my SLC 5/05 plc as Modbus master talking directly to both Modbus devices without the DSPLE but the firmware version of my clients plc on site doesn’t support the plc being used as a Modbus master without upgrading. They are nervous about doing this which is why I am looking at using the DSPLE as a back up plan.

Below is a summary of what I need to do:

My Modbus devices are nodes 1 & 2 and they are connected to the RS485 port of the DSPLE. The cable goes from the RS485 port to node 1 and then on to node 2.

My SLC 5/05 plc is connected to the DSPLE by Ethernet.

I need to read 20 holding registers from each Modbus device starting at address 40258.
I need to copy the data from these holding registers to plc addresses N27:0 – N27:19 for Node 1 and plc addresses N27:20 - N27:39 for Node 2.

I need to write to 10 registers from address 40001 in each Modbus device.
I need to copy the data from plc address N27:40 to address 40001 in Modbus Node 1.
I need to copy the data from plc address N27:50 to address 40001 in Modbus Node 2.

Anything you can do to help me get this working would be greatly appreciated.

In Red Lion, after you get the ports set up correctly for serial Modbus and Ethernet to the SLC, this is roughly five minutes and a few dozen clicks and keystrokes. Once you know the basics of how Blocks and Mapping work in Crimson, it's super-easy.

When a data Block is red in Crimson 3 software, it is a "Device to DSP" block, which is what it sounds like: the DSP reads the data periodically (you can specify the milliseconds between reads) from that device.

You can map a data Block on the left side Communications pane to an address in another device by selecting that device and its data types from the right side Resources pane. The DSP will perform the reads from the "Device to DSP" block, then promptly write that data to the other device address you specify. You can see the direction of the data in the ">>" characters in the screenshot.

Calling this sort of Crimson 3 application a "program" is almost an exaggeration: it's really just a configuration of the DSP's heart-and-soul function: "Read from one device, write to another"

Here'a a screenshot:

Thanks again Ken,

I made contact with RedLion Support yesterday and they told me what was wrong with my config. As shown in your screenshot I needed to use the DF1 Master driver in Network Protocol 1. I had chosen DF1 via PCC/EIP and it wouldn't work. I am now reading data from the SLC through the gateway but not yet communicating the the Modbus devices on the RS485 port. I'm hopeful it's just a cabling issue which I'm now working to resolve.

All sorted now after some jiggery *****y with the pin outs on the RS485 cable. It looks so simple now it's all done. Like most things, it's easy when you know how.

Thanks for the updates !

Red Lion stubbornly uses non-intuitive names for some of their communication drivers and I really wish they had better notes and examples.

"DF1 Master" is really DF1 Full Duplex when put on an RS-232 port, and PCCC via legacy CSPv4 when put on an Ethernet port.

"DF1 via PCCC/EIP" would be better named "MicroLogix 1100/1400" or "PLC/SLC Data Tables via EtherNet/IP"

For about the past 15 years, the SLC-5/05 has supported the PLC/SLC Data Table access protocol (Programmable Controllers Communication Code = PCCC) transported over Ethernet by both the legacy CSPv4 Ethernet protocol and EtherNet/IP.

A small number of Series A SLC-5/05's can't be upgraded to the necessary FRN5 or higher firmware. Any SLC that has a Series C daughtercard with a 10/100 port already supports both protocols.