Comunication Computer - Plc A2sh.

[Héctor. 1]

Good Morning. I need to comunicate the computer with a PLC A2SHcpu from a distance 150 meters. I am using a A1SJ71UC24-R4 module conected in the rack of the PLC and a FX-485PC-IF conected to a computer, but then comunication does not work. I have used a module A1SJ71UC24-R2 for to comunicate PLC - computers. I need to know if the serial cable RS-232C what I am using for to comunicate the Computer with the FX-485PC modem is the adecuate for to program the PLC using module A1SJ71UC24-R4. Would I need any program or something else for configurating the module?, or this work only with that conection in the file attached. The cable RS232C for conecting from converter FX-485PC-IF to Computer is: DB25 Male - DB9 Female SD (pin 2) - RD (pin 3) RD (pin 3) - SD (pin 2) RS (pin 4) - CS (pin 7) CS (pin 5) - RS (pin 8) DR (pin 6) - ER (pin 6) SG (pin 7) - SG (pin 5) ER (pin 20) - DR (pin 4) In the file is marked with red the part with problems. Best Regards. Tanks, for your time and answers. CORREO.xls

[panic mode 246]

screenshots of cable diagrams in the excell file are correct but i think your pins assignment for RS232 is wrong. according to my little reference it should be: TXD-3 RXD-2 RTS-7 CTS-8 DSR-6 SG-5 DTR-4 so if i'm not missing anything cable from DB25 (485PC-IF) to a DB9 female (goes to PC) should be: 2-2 3-3 4-8 5-7 6-4 7-5 20-6 Next thing is to check the wiring from PLC to 485PC-IF. Make sure to use proper cable type (I would look for two twisted pairs with overal shield) with four 330 Ohm terminating resistors as shown in manual (see pic).

[waynes 8]

DB25(485PC-IF) to DB9 (PC) should be: 2-2 RXD-TXD 3-3 TXD-RXD 4-8 RTS-CTS 5-7 CTS-RTS 20-6 DTR-DSR 6-4 DSR-DTR 7-5 SG For simplification, you can bridge RTS & CTS, DSR& DTR on each end of the cable, ie.: 2-2 RXD-TXD 3-3 TXD-RXD 4&5; 7&8 RTS& CTS bridges on either side of comms cable (not connected) 20&6;4&6 DTR& DSR bridges on either side of comms cable (not connected) 7-5 SG The latter cable can be used safely if XON/XOF (software handshaking) is used. The first cable is only necessary if using hardware handshaking. Check out http://www.hardwarebook.net/adapter/serial/9to25serial.html for the serial pin layouts. Panic mode, why use 330ohm resistors? All you need to do on the 485 is pull the conductor into a common tri-state when no comms are active. This means that both transceivers are talking on the same plane. You can also use 120ohm resistors if you don't have luck with the 330ohm resistors. I think the profibus terminating resistance is 330ohm, also cc-link high performance, otherwise 110/120 ohm would do the job perfectly. Hope this helps! OK, I got the harware and software manual. Now check the hardware manual and you will see that they bridge the connections I mentioned earlier. FX_485PC_IF_Hw_Man_JY992D81801A.pdf FX_485PC_IF_User_Man_JY992D53501A.pdf

[panic mode 246]

termination resistors in circuit are required for normal operation. in my experience they can be omited in some cases like very short cable, low baud rates, low noise level etc.. but for 100m cable length i would be surprised to see properly working connection. as said it might happen if the noise in place is very low (never been case in my projects) or com speed is low (i prefer to use highest reasonable speed when possible). resistor value is different for different networks. generally values will be lower for higher speed network. lowering impedance helps improve noise imunity at the cost of more power disipated at the transmitting node. profibus terminator is a bit different. it is the only fieldbus terminator i can think of right now that uses three resistors instead of one. additional resistors are used to balance line by pulling the ends to +5 and 0V. Tristate is nice concept it is not a problem when you have control of the circuit at the low level but how can you tristate TxD on say A1SJ71 or 485PC-IF in case like this? You would have to write own software to do this and even so I doubt it would help. When you tristate output, line is floating (high impedance). This doesn't help reduce noise, it's quite the oposite.

[waynes 8]

panic mode, you mentioned that the higher speed networks use lower resistance? Why does the high performance cc-link use a 130ohm resistor and the normal cable uses a 110ohm resistor? I have recently installed a RS485 network that reaches well beyond 100m (about 350m) and I succesfully used 120ohm resistor on either side. As you mentioned, no plant goes without noise, and this one definately has, as it is an automobile manufacturer. Anyway, did Héctor get the answers he required?

[panic mode 246]

well i would be more than interested to hear from Hector how this go. as for resistance values, i've seen plenty incorrectly terminated ("overterminated") systems that still worked ok.in one place i've seen small 6-7 node network where someone put terminator on every single node. it's not that 10-20% change like in example you posted would make much difference but since this was CC-Link, Japanese just had to do something different. maybe this is why their cables are red too