Parker Gemini GT6 Series Hardware Installation Manual page 45

Testing the Cable
RS-232 Daisy Chain Guidelines
RS-485 Multi-Drop Guidelines
44
Gemini GT6 Hardware Installation Guide
Use the following two procedures to test your null modem cable, and verify that it
is working properly.
"Loop Back" Test
1. Connect one end of your RS-232 cable to your PC, palm PC, or HPC. Disconnect
the other end of the cable from the drive.
2. Connect pin 2 to pin 3 on the drive end of the RS-232 cable.
3. Launch Motion Planner and select "Test Com Port" from the "Communications"
menu.
4. If you receive a "Communications OK!" response, your cable is good.
3. Under "options", select "show hex."
4. With pins 2 and 3 at the drive end of your null modem cable open , typing "DRES" in
the terminal will produce the response "DRES 0A00".
5. With pins 2 and 3 at the drive end of your null modem cable shorted, typing "DRES"
in the terminal will produce the response "DRES 0A00 0A00".
If you are continuing to have trouble with communications, proceed to Verifying a
Null Modem Cable.
Verifying a Null Modem Cable
1. Connect one end of your RS-232 cable to your PC, palm PC, or HPC. Disconnect
the other end of the cable from the drive.
2. With no data being transmitted, measure the voltage on the RS-232 cable's transmit
pin (should be pin 2). The voltage on the transmit pin should be in the range
-3VDC to -12VDC.
3. Measure the voltage on the RS-232 cable's receive pin (should be pin 23). The
voltage on the receive pin should be zero volts.
4. Verify that the cable's transmit pin connects to Pin 2 on the Gemini's RS-232/485
connector.
This completes the test.
All drives in an RS-232 daisy chain must be configured as follows:
• Echo must be on (ECHO1)
• Error level must be set to a value greater than Ø. (See ERRLVL command).
All drives in an RS-485 multi-drop must be configured as follows:
• Echo must be off (ECHOØ)
• Error level must be set to either 2 or Ø. (See ERRLVL command).
• Connect RS-485 cables before applying power to the drive.
(Reconnecting the cables with power applied may cause the drive to interpret
intermittent connections as RS-232 hardware handshake signals; this may result in
shutdown of the RS-485 interface. If this happens, reset the drive to re-enable the
RS-485 interface.)