MKS Granville-Phillips 358 series, Instruction Manual

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Chapter 4
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Series 358 Micro-Ion Controller Instruction Manual - 358013 - Rev. B
RS-232 Handshake Line
Summary
CTS, DSR
Set the computer to indicate that controller may output the next byte in its
message. As shipped from the factory these lines are forced “TRUE” by the
switch settings of the controller RS-232 printed circuit board. Thus the
controller will automatically assume the host is ready to receive. See Figure
3-12 on page 39 for the location of these switches.
DCD
Tested by controller when a character is received. The character will be
ignored unless DCD is “TRUE”. As shipped from the factory, this line is
forced “TRUE” by the switch settings.
DTR
Always asserted by the controller. A “power ON” indication.
RTS
Negated by the controller on power-up. Asserted by the controller upon
receipt of a message terminator. Negated after transmitting the terminator of
the controller's response to that message.
Reversing RTS Polarity
If switch 2 is open on power-up, the controller will apply the opposite
polarity to RTS from that described above. When used in this mode, RTS
may be connected to the CTS input of the host computer. This violates the
RS-232 standard, but is a commonly used implementation.
4.16 Connecting RS-485
Computer Interface
For instructions for setting up this interface, see RS-485 Computer Interface
Setup on page 42.
Connectors J1 and J2 on the rear panel of the controller (Figure 3-16) are
wired in parallel and are interchangeable. Connection can easily be made
by “daisy chaining” gauge Controllers together with the signal from the host
computer going into one connector then out the other to another gauge
Controller and so on.
The maximum total cable length is 4000 ft. The maximum number of
devices connected is 32.
The control of data over the RS-485 interface is handled by a Half-duplex
Command/Response mechanism.