FAQ: When the personal computer (PC) serial port connection is disconnected from the controller, why does the SMC-2000/3010/4000 controller become unresponsive?
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The SMC-xxxx products use hardware handshaking, and if there are commands in the program that send unsolicited messages (MG, IN commands) they are transmitted from the default port. The serial port is the default port. The apparent "lock up" is caused when no device connected to the serial port. (The controller sends a character and waits for the hardware handshaking signals before it can continue to the next command.)
Since MG commands are typically used for debugging. These messages can be removed and the "lock up" will no longer occur. However, when it is preferred to leave the debugging messages in the program for use at a later time, there are at least three methods for handling this.
1) Use search & Replace to change all MG command into NOTE: MG
2) Create a user variable such as "DEBUG" in the program.
Use this variable in the program prior to writing any MG message command.
Be sure to initialize it to zero whenever power is cycled; such as DEBUG=0
#AUTO
DEBUG=0
Use DEBUG in the program with the MG commands:
IF (DEBUG=1)
MG"WAITING FOR HOME SIGNAL"
ENDIF
All three lines above can put the in one line to save program space, the SMC controllers allow 80 characters per line.
IF (DEBUG=1); MG"WAITING FOR HOME SIGNAL"; ENDIF
This will skip the messages while DEBUG=0. When connected online with the PC, type DEBUG=1 in the terminal window and debug messages will again be displayed. Prior to going offline, either set DEBUG=0 from the terminal or cycle power.
3) Messages can be diverted to an unopened Ethernet handle without causing an error or lock up. Use the CF command to send messages to an Ethernet handle.
Note: When connecting to an SMC-3010 or SMC-4xxx controller via Ethernet, Yterm automatically sets the default port (CF Command) to the handle on which the connection was made. When the BN command is executed, the default port is one of the configuration settings that are saved. Make sure to include any important configuration setting in the program to avoid confusion about the actual value of the parameters.
ARGUMENTS: CF n where n is A thru P for Ethernet handles 1 thru 16, S for serial port.
4) The last, and least elegant solution is a jumper plug for the SMC serial port. This plug would connect the RTS and CTS pins; effectively making the controller believe that hardware handshaking is connected and working.
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Please read and understand the product instruction manual before installing, servicing or operating Yaskawa products. FAQ content and illustrations are provided as technical advice to augment the information in manual, not supersede it. It is not possible to give detailed instructions for all types of installation or support activities. The information described in the FAQs are subject to change without notice to improve the product or FAQ. Yaskawa assumes no responsibility for errors or omissions or damages resulting from the use of the information contained in any FAQ. All warnings, cautions and product instruction for product use must be followed. Installation, operation and maintenance should be carried out by qualified personnel. Failure to observe these and other precautions highlighted in the product manuals will expose the user to high voltages resulting in, serious injury or death. Qualified personnel are defined as individuals who are familiar with the installation, starting, operation and maintenance of Yaskawa products of the type described and have proper qualifications to perform the work.
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