The following describes the hardware / software conditions: no RS232 serial port notebook computer, Omron CPM2AH-60CDR type PLC, Cx-Programmer V5.0 programming software.


1. Cx-Programmer V5.0 is not stable with PLC:
Computer and PLC connection: computer USB port (the computer does not RS232 serial port) ← → [USB to RS232 cable USB plug ← → USB to RS232 cable (the computer has been installed driver, and the default COM4 port has been set to COM1) Middle part ← → USB RS232 cable for RS232 cable ← → [[RS232 connection between computer and PLC RS232 → connection between computer and PLC cable ← → connection between computer and PLC RS232 Head]] ← → PLC’s RS232 female.

The above single brackets for the USB to RS232 cable, double brackets for the computer and PLC connection cable. The connection between the computer and the PLC is as follows: (1) Male (for connecting the PLC) 2, 3, 9, respectively, with the mother of 2,3,5 (for connecting the computer or USB to RS232 cable) short This is the official connection method of Omron; (2). Male and female 2-2,3-3,5-5 are shorted, which is the conventional connection method of RS232 cable. Later proved by practice: the above two kinds of computer and PLC connecting cable can be used. The first kind of cable communication is stable and reliable. For the second cable, when the computer and PLC through the VC application communication between the poor results, easy to drop frames (with the serial debugging assistant can see), only when the computer and PLC shared power (total) when not problem found. Therefore, please use the first type of connecting cable.

There is time the computer and PLC can communicate properly, there is time not – show “Modem has been selected to continue code?” Failure (in fact, “code” should be “?”), Once the fault information, The following error message appears:

When the communication is not on, I used to clone back to the previous normal operating system, re-install Cx-Programmer V5.0 programming software and other methods, but also normal communication, but once the disconnection may not be on the communication. Several times also found that some procedures can communicate with the PLC, and some procedures but not! Therefore, the author will be able to communicate the PLC program first backup, and then delete all the instructions in the program, and finally the target program instructions all copied over (copy of the Notes can be automatically copied), so that the computer can communicate with the normal PLC The! But – the next time this program may not be able to communicate properly!

According to the communication error message “Modem has been selected, to continue code?”, I found the solution: right click on the desktop “My Computer”, then click “Properties” – “Hardware” – “Device Manager” , Then double-click the “modem”, then right-click the expansion of the modem model, click “disable” on it.
The same time as
In addition, the correct connection is as follows: the computer did not boot or (and) PLC is not powered (otherwise charged plug the communication port may cause damage to the communication port (although this chance is not, but you’d better not luck)) situation Connect the USB to RS232 cable, connect the computer to the PLC cable, and then connect the computer to the PLC via the Cx-Programmer.

Please note: USB port is not casually plug can be, the key to ensure that the device manager RS232 port for COM1. The author of the computer on this situation: the original has been the default RS232 port from COM4 port to COM1 port, but plug the following USB port is corresponding to the RS232 COM4 port (COM1, COM3 is being used), can not connect the computer and PLC; Plug the USB port corresponding to the RS232 COM1 port (COM2, COM4 is being used), you can connect the computer and PLC.

2. Cx-Programmer V5.0 communication with the PLC interference:
If the Cx-Programmer is online, the computer and the PLC are connected and are in a communication state, the communication error will occur when the device is shut down (nearly 20 AC contactors are disconnected at the same time). The communication error will occur and the computer and PLC connection will be interrupted. And when each boot (nearly 20 AC contactor at the same time pull) but there will be no communication error situation.

Solution: Reconnect the PLC. If you are a perfectionist, you can add an RC RC module on each contactor coil (approximately 60 or so per RC module), and there may not be a communication error (but I have not tried it). .

3. Computer and PLC connection cable test:
Because you think of the connecting cable between the computer and the PLC (the first conventional connecting cable) is 2-2 short, 3-3 shorted, 5-5 shorted, consider connecting the computer and PLC directly with USB ← → RS232 cable Up, if so, then do not save a connection cable? The following is a direct use of USB ← → RS232 cable to connect the computer and PLC test results:

There is time for the first communication when the following error: “the selected port is occupied by another application”; the second communication when the following error:
The same time as
Why the computer through the above two kinds of connecting cable and PLC connection is no problem, and direct use of USB to RS232 cable and PLC connection is not it? The following is the analysis process:
Type 1 possible: the cause of the impedance. Although the two connecting cables for the direct connection, there is an impedance exists, more of this impedance can be connected normally. But this reason seems very far-fetched, even the author himself can not believe.

The second possibility: the USB to RS232 male and PLC of the mother of poor contact, and add a cable can be connected to normal – USB to RS232 male and the connection line of the mother contact is good, the connection line of the public Head and PLC’s mother contact good. The guess comes from the author encountered a computer failure: a computer mouse can not be used, another for a mouse normal, the faulty mouse to other computers can be normal use. Finally, suspected mouse connector and motherboard connector bad contact, the mouse plug will be broken and then coated with a layer of solder, the results of the use of normal! But for USB to RS232 male and PLC’s poor contact with the mother of this speculation, I think the possibility is not – because he can not explain the “selected port occupied by another application” of the fault.

Finally think of another possible: USB to RS232 directly connected with the PLC is equivalent to USB to RS232 serial port and PLC serial port 1-1,2-2,3-3,4,4,5,5,6-6, 7-7,8-8,9-9 one by one corresponding to the connection, but through the connection line is only 2-2,3-3,5-5 three pairs of terminals connected, which shows 1-14-4,7- 7,8-8,9-9 at least one pair can not be connected, otherwise there will be problems, and this is also possible to damage the PLC and computer communication port. I think that is the reason.

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