Red Lion PCU - Manual (Page 42)

Overlap/Deadband (db-2) (Cont’d)
In practice with the secondary output, observe the controlled process
characteristics and if the process remains above setpoint with a sluggish
return, increase the relative gain. Similarly, if the process drops too sharply
with an overall saw-tooth pattern, decrease the relative gain. Alter the
deadband/overlap until a smooth response in the controlled process is
observed during band transition.
SERIAL COMMUNICATIONS MODULE (6-SC) (OPTIONAL)
When communicating with a PCU unit via the serial port, the data formats
of both units must be identical. A print operation occurs when the user input,
programmed for the print request function is activated, when a “P” command
is sent via the serial communications port, or after the time expires for the
automatic print rate, if enabled. Serial communication is covered in detail in
RS485 Serial Communications Interface, page 47.
Baud Rate (bAUd)
The available baud rates are:
300, 600, 1200, 2400, 4800, or 9600
Parity Bit (PArb)
Parity can be odd, even, or no parity.
Address Number (Addr)
Multiple units connected on the same RS485 interface line must each have
a different address number. A value of 0 does not require the address specifier
command, when communicating with the PCU. The address numbers range
from 0 to 99.
Abbreviated or Full Transmission (Abrv)
When transmitting data, the PCU can be programmed to suppress the
address number, mnemonics, units, and some spaces by selecting YES. An
example of abbreviated and full transmission are shown below:
NO - 6 SET 123.8F Full Transmission
YES - 123.8 Abbreviated Transmission
Print Rate (PrAt)
The PCU can be programmed to automatically transmit the selected print
options at the programmed print rate. Selecting 0 (zero) disables the
automatic print rate feature.
PrAt - 0 to 9999 seconds
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Figure 20, Operation (db<0)