SLC 5/01 communication from my PC!!

D

Thread Starter

Derek Haywood

Hello, I have just purchased a SLC 5/01 second hand. Unfortunately my background is Electrical & Instrumentation & have never really messed around in the comms. area. Therefore I am after the best( & least expensive ) way to communicate with the SLC 5/01. It has a DH 485 port & thats it, I have looked at the AB Web site & they mention a DH-485/RS-232c interface module.(1747-KE) Is this the correct way to go as my distance between the PC & PLC is approx. 30 meters & I believe that RS-232 is only good for approx. 15 meters. I have also read that because I only have one PLC that I will not need the 1747-AIC link coupler, is this correct? Im also not sure if its best to use the serial port on my PC or the modem. If you decide to answer my simple questions maybe you could start with a basic outline of DH-485 & RS-232. Thanks Heaps!! If you any approx. prices on equipment I may need ( Cards,Cables etc ) it would also be appreciated.( Im from Down Under, Australia ) CHEERS!!
 
C

Crucius, Wesley

You don't really indicate what the purpose of your communications with the PLC is, but I'll assume it is primarily for programming/debugging, and as such I think all you really need is a -PIC module. If you are running Win2k, you'll need the latest version of RSLogix/RSLinx in order to get support for the PIC. You don't mention anything about programming software, so I guess it must have come with the unit?
 
A

amora fibrianto

DH-485 is built in RS-485. RS485 has different electrical spec. with RS-232. Don't mess around with it. Yes, you gonna need an interface module, and I think you need a PIC module. I never try an RS-232 to RS-485 converter that available in common computer shop to link my DH-485 RG connector to 9 Pin RS232 in my computer. anybody ?
 
L
I had hoped a real Rockwell expert would answer, but so far none. Just lots of incomplete answers. DH485 is *MORE* than just RS-485. An RS-232/485 converter will NOT help you. DH485 is a high-speed token bus - NOT high-speed in baud as it works fine at 19,200 baud. But high-speed in that it expects fast token rotation etc. This means it pretty much requires a dedicated CPU to manage the DH485 (or highly optimized interrupt routine in a single CPU system). It has been acknowledged before on this list that DH485 cannot be reliably sent thru non-DH485 aware radio modems or Ethernet tunnels because of this need for steady, gap-less communications. MicroLogix does this RS-232 to DH485 trick with a "regular isolated RS-232 to RS-485 converter" (the AIC+) because when set up to DH485 it is running pure DH485 protocol bytes on it's RS-232 port (not DF1, the AIC+ has no CPU). I would guess that RSLinx does NOT even try this trick - never sends DH485 protocol out a PC's RS-232 port. So an AIC+ or other RS-232/485 converter would not get your PC hooked up to your SLC5/01. (I think the AIC you mention is a different unit than the AIC+ I've mentioned here - I'm not programmed will all the RA jargon & numbers. Some of these RA guys sound like they are from a different planet! A comedian at an ISA dinner could get a lot of laughs out of a routine spoofing two old RA users meeting.) So all the people saying you need "Module X" & "Software Y" are correct. Bottom line is you'll need a box/card with a dedicated DH485 CPU to talk to your SLC5/01. This means either a box with 1xDH485 port and 1xDF1 RS-232 port or a plug-in card with DH485 for a PC (or PCMCIA card). The software will need to talk to this box/card - for HMI/OPC you will find options which do not require RSLinx - but for programming the SLC5/01 with RSLogix you will need RSLinx. RS-232 is good for 2500pF of capacitance per driver - the age-old "45 feet/15 meter" rule is only suggested in an appendix to RS-232 for cases where you don't know the spec of your cable! If you buy good, low-capacitance cable (like Belden 1421A) you can run RS-232 legally up to 55m - but make sure one end is optically/galvanically isolated so you don't invite grounding problems. RS-232 to a PC is one of the most fragile data comm designs you could pick. Better to run the DH485 farther and RS-232 shorter than the other way around. regards Lynn August Linse, Senior Software Engineer 15353 Barranca Parkway, Lantronix Inc, Irvine CA 92618 [email protected] www.lantronix.com Tel: (949)300-6337 Fax: (949)453-7152
 
S

Stuart Cameron

RSLinx running the netAIC/PIC driver connected to a netAIC via the PC serial port. The DH485 cable connects the netAIC to a AIC which is connected to the SLC5/01. This runs under WIN9x and NT, but not WIN2k [netAIC/PIC driver not written yet] We have used this setup on multiple jobs, usually to MLC1500 plc's, with no problems. This allows you to program or connect an HMI over the network Professional Electrics 123 Blenheim Road PO Box 8563 Christchurch New Zealand
 
J

Joe Jansen/ENGR/HQ/KEMET/US

To elaborate...... (Lynn Linse wrote) <snip> >I would guess that RSLinx does NOT even try this trick - never sends DH485 >protocol out a PC's RS-232 port. So an AIC+ or other RS-232/485 converter >would not get your PC hooked up to your SLC5/01. (I think the AIC you >mention is a different unit than the AIC+ I've mentioned here - I'm not >programmed will all the RA jargon & numbers.) <snip> Sadly, I am. The AIC module has 3 DH-485 ports, 1 trunk and 2 nodes. If you are running DH-485 as anything other than point to point, you will need an AIC module at each point. The trunk line runs between modules, and the devices (PLC's, panelviews, Programmers, or whatever) plug into the node ports on the AIC. the AIC+ (aka -NET-AIC) has a trunk port, a 9pin D-shell that will do RS-232, and a 9 pin mini-din for talking to the micrologix or SLC's that have a DF-1 port on them. Although I haven't cracked one open, I would guess that the AIC+ has the processor internal, since it does have the baud rate selector on the front of it, and comm indicators at each port, plus requires 24VDC power (usually picked up from the 9 pin din, or from external supply). The AIC is, as you mention, just a dumb block that ties the ports together, but it does do some coordination of the signals. >So all the people saying you need "Module X" & "Software Y" are correct. >Bottom line is you'll need a box/card with a dedicated DH485 CPU to talk >to your SLC5/01. This means either a box with 1xDH485 port and 1xDF1 >RS-232 port This is the PIC module, available from AB. They are also available from B&B electronics (Model: 232ABRJ45) I paid about $190 USD if I remember correctly. > or a plug-in card with DH485 for a PC (or PCMCIA card). Allen Bradley PN 1784-PCMK Series B. Careful installing the drivers for this one, as it gets tricky. > The software will need to talk to this box/card - for HMI/OPC you will >find options which do not require RSLinx - but for programming the SLC5/01 >with RSLogix you will need RSLinx. This is true. One caveat on this: If you are running windows NT (not sure about 2K) and you install the PIC driver, it will take over your comm port. Because of the tricks that Mr. Linse mentioned as far as critical timing et. al. the PIC driver for RSLinx replaces comm.drv with abkt.drv. What this means is that Windows no longer has access to the standard comm driver. If you use the RS-232 port on an NT machine for anything else, you will have to un-install the pic driver from RSLinx and reboot the computer anytime you want to use the port for anything else. No, there is no other way under NT. 98 and 95 don't have this problem, as they can swap the driver 'on-the-fly', so to speak. The problem is the Hardware Abstraction Layer in NT. >RS-232 is good for 2500pF of capacitance per driver - the age-old "45 >feet/15 meter" rule is only suggested in an appendix to RS-232 for cases >where you don't know the spec of your cable! If you buy good, >low-capacitance cable (like Belden 1421A) you can run RS-232 legally up >to 55m - but make sure one end is optically/galvanically isolated so you >don't invite grounding problems. RS-232 to a PC is one of the most fragile >data comm designs you could pick. Better to run the DH485 farther and >RS-232 shorter than the other way around. To do this, buy a the PIC or PCMK, and 2 of the AIC modules (NOT the AIC+ or NET-AIC). Put 1 AIC near the plc, and use the cable that is included with the AIC to connect to the PLC's port. Run standard, plain old boring 3 conductor shielded cable to the other AIC module located near the computer.(NOTE: If your distributor is any good, he will try to convince you of the evils of using regular cable, and try to convince you to use the 'special' cable. Ignore him. He's just doing his job, but I have NEVER had a problem with regular cable on runs of 100m or more). plug the computer into the port on the 2nd AIC and VIOLA! you probably won't be communicating! After everything is connected, you have to play "guess that baud rate" to get it talking. The DH-485 drivers are absolutely no help on this. for a 5/01, try starting at 1200 bps. Play with it until you get it talking. You will know it works when the litlle PLC icon appears in the RSLinx window. Although I don't know if I would qualify myself as an expert, I have been working with SLC's since the 5/01 was new, and we looked ahead to the days of the "amazing and new" 5/02. Hope this helps! --Joe Jansen
 
Top