0172851 JOHNSON ARMATURE

Illustration 1 g00669454
CCM/Host equipment Remote Connection with Modems
(1) CCM
(2) CCM RS-232C port
(3) Answering modem
(4) Telephone line
(5) Originating modem
(6) Computer's RS-232C port
(7) Host equipment You should verify the CCM is operating correctly before attempting a remote connection via modem. Verifying correct operation can be accomplished by following the instructions in Operations and Maintenance Manual, SEBU7014, "Initialization for Direct Connection" under the Operation Section in this manual. The user can verify proper operation of the CCM at the location. The user can also become familiar with the CCM. Perform the following procedure in order to initialize communication between the host equipment, the modems, and the CCM. Make sure that the following equipment is available:
A personal computer with a terminal emulator software program Refer to "Caterpillar CCM PC For Windows: Getting Started Manual" for specifications on the PC. The user is responsible for understanding the operation of the PC.
The proper RS-232C cables are required for the particular installation. A RS-232C cable must be temporarily connected from the PC to the Answering Modem. Refer to the Operation and Maintenance Manual, SEBU7014, "RS-232C Cable Requirements" in the Operation Section of this manual.
The two modems must support the Hayes AT command set. This is necessary for both the Answering Modem and the Originating Modem.
The CCM PC For Windows software is optional. The PC software for the CCM is recommended for troubleshooting assistance.Note: Some personal computers will have an internal modem. The internal modem may be used as the Originating Modem. The internal modem must be compatible with the Answering Modem. Consult the instructions for the two modems.Perform the following procedure in order to initialize communication with the CCM and the Answering Modem. The Originating Modem is set up later by the PC software or remote host equipment. The user is responsible for understanding the remote device and modems.Note: In the following steps, the PC and the modems should be turned OFF before you change the cables on the serial ports. When power is reapplied, the modem must be powered up first.
The CCM should be installed with all of the wiring. Refer to the Operations and Maintenance Manual, SEBU7014, "General Wiring Diagram" and "General Specifications for Wire and Cable" in this manual.
Determine the communication parameters for the installation. The default rate of communication (bits per second or bps) is 9600. The remaining default settings from the factory are no parity, 8 data bits, and 1 stop bit. These parameters will work well in most installations. Use the Operation and Maintenance Manual, SEBU7014, "Communication Parameters - Identify" in this manual to determine the parameters of communication that are stored in the CCM. Note: The RS-232C serial port communication baud rate is often referred to as the DTE speed. The phone port communication rate is often referred to as the DCE speed.
Connect the RS-232C port of the Answering Modem directly to the RS-232C port of the PC. This connection is temporary. This connection is required to set up the Answering Modem.
Use the terminal emulator on the PC to set communication parameters for the RS-232C port. Use the values that were chosen in step 2. Note: The symbol Ø indicates the number zero.
Several commands must be sent to the Answering Modem that set the parameters for communication to the proper values. The examples are Hayes AT commands. Actual command sets vary widely between modem manufacturers. Consult the manual for the modem.
Table 1
Typical Answering Modem Setup Commands
Item Explanation Command Example Command for User's Modem
a Set the modem to the factory defaults. This is important if the setup of the modem is unknown. AT&F
b Set to communicate in error control and in asynchronous mode.
If the modem does not support this command, enter the AT command for error control. Set to communicate in asynchronous mode with a separate command (Item c). Otherwise go to Step d. AT&Q5
c Set to communicate in asynchronous mode.
Note: If the &Q5 command is supported, the modem is already in asynchronous mode, and this command should not be sent. AT&QØ
d Set Auto answer to ON. This tells the modem to answer the phone line after the first ring. If left at Ø, the modem will never answer an incoming call. The value of this register can be seen with the ATSØ? command. ATSØ=1
e Set Flow Control to XON/XOFF. This turns off RTS/CTS hardware handshaking between the modem and CCM since the CCM does not have RTS or CTS lines. It turns on the XON/XOFF software handshaking. AT&K4
f Set DCD to track status of carrier detect signal. This causes the DCD line from the modem to follow the state of the phone line carrier. When the call to the CCM's modem has been made and the modem to modem handshaking is done, the DCD line will change and allow the CCM to recieve data.
Note: This is very important. If the DCD line is not at the right state, the CCM cannot receive data. AT&C1
g Set DTR to monitor DTR signal and hang up and reset modem on an on-to-off DTR transition. This causes the modem to hang up and reset if the CCM drops the DTR line. AT&D3
h Result codes do not have to be returned. Or, if the result codes are returned, the codes must be in originate mode, but not in answer mode. ATQ2
i Set DTR transition response delay to maximum value less than 10 seconds. This example would cause the modem to hang up the line 2.5 seconds after the DTR line from the CCM changes.
Note: Refer to your particular manual. Some modems specify the time in 1/100th of a seconds, and some in 1/10th of a second. ATS25=25Ø
j Set delay before forced hang-up to maximum value less than 3 seconds. ATS38=2
k Write the setup parameters into memory Ø. When the setup parameter are written, any that were not changed are stored into the memory. AT&WØ
l Set to recall memory Ø on reset. AT&YØ
m View the modem active profile. This is an optional command that allows the user to view the above parameters stored in