MKS Granville-Phillips 358 series, Instruction Manual

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Service
Series 358 Micro-Ion Controller Instruction Manual - 358013 - Rev. B
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8.8 RS-232 Troubleshooting
Because the RS-232 “standard” is found in an array of configurations, the
first thing to do if trouble arises is check the following configuration options:
1. Check switch settings.
Be sure the baud rate, character format and framing, and interface
protocol are matched to your host computer or terminal's
requirements. Note that there may be several mismatched parameters.
Check to see if your computer requires the reversed-polarity RTS
convention.
2. Check the interface wiring.
The pin designations for the RS-232 connector are listed in Table 3-5
on page 38. Note that the “received” and “transmitted” data lines are
defined as seen by the controller. Many companies supply “null
modems” or switch boxes for the purpose of reconfiguring the control
and communications lines for particular applications.
3. Check the command format.
Be sure the strings you output to the controller are in accord with the
syntax defined in
Preparing to use RS-232 Computer Interface on
page 87.
Table 8-5 RS-232 Troubleshooting Guide
Symptom Possible Cause
Microcontroller reset LED lit or
flashing. See Figure 3-12 on page 39 Microcontroller failure
No response or garbled output Baud rate incorrect
Character length incorrect or stop bit(s) incorrect
Bad cable.
OVERRUN ERROR message Stop bit(s) incorrect, host software failure
PARITY ERROR message Parity incorrect
SYNTAX ERROR message Message to controller not in accord with specified syntax or failure to assert DCD
handshake line