Watlow Series 96 - Manual (Page 30)

Input Errors
(error number in top display, percent output in bottom display)
Modbus Register #101 r; (values in parenthesis below).
[Err1] (1) Error 1 indicates the input is too low to measure.
[Err2] (2) Error 2 indicates the input is under the sensor range.
[Err3] (3) Error 3 indicates the input is over the sensor range.
[Err4] (4) Error 4 indicates the input is too large to measure.
No error = (0)
5 . 1 1 ■ F e a t u r e s Wa t l o w S e r i e s 9 6
Bumpless Transfer
When the sensor opens (fails), the controller switch-
es from automatic to manual operation. If bumpless
transfer is active when the sensor fails, the control
output (or outputs) will remain stable — a bump-
less, or smooth, transition.
If the Failure Mode [FAIL] (Global Menu) is set to
bumpless [BPLS] and the process has stabilized at
a ± 5 percent output power level for 2 minutes prior
to the sensor break, and that power level is less
than 75 percent, the controller switches to manual
operation at the last automatic power level. If these
conditions are not met, the output goes to 0 percent
power (output disabled).
If Failure Mode is set to manual [MAn], the Series
96 switches to manual operation at the percent
power value of Manual Default Power [MAn]
(Global Menu). Manual operation provides open-
loop control of the outputs from a range of -100 per-
cent to 100 percent output. The Series 96 allows a
negative output value only when Output 1 or 2 is
set to cool.
When the controller returns to closed-loop control,
it uses the previous set point value.
Figure 5.11 – Bumpless transfer.
Note: The bumpless transfer feature will not appear if the
ramping software option has been ordered (96XX-XXXX-
AAXX).
Time
Temperature
40%
S
B
2 minutes
0%
Set Point Actual Temperature
Output Power
Power
100%
Communications
A Series 96 controller can also be programmed and
monitored by connecting it with a personal computer
or programmable logic controller (PLC) via serial
communications. To use this communications option,
a Series 96 must be equipped with a EIA/TIA 485
(96_ _ - _ _ _U - _ _ _ _) or EIA/TIA 232 (96_ _ - _ _
_R - _ _ _ _) communications board installed for
Output 4.
Use of the EIA/TIA 485 requires that your PC or
PLC use the EIA/TIA 485 interface in half duplex.
Purchase an interface converter which communi-
cates in half duplex when using a PC or PLC with
an EIA/TIA 232 communications port. You must use
the EIA/TIA 485 option to communicate with more
than one control. This option directly supports up to
32 devices on a network.
To view or change controller settings with a person-
al computer, you need to run software that uses the
Modbus RTU protocol to read or write to registers in
the controller. See Chapter Six for the Modbus regis-
ters. These registers contain the parameter values
that determine how the controller will function and
the values that reflect the current input and output
values of the system.
Decimal points are not sent or received in Modbus.
To determine decimal point locations, read the deci-
mal parameter [DEC1]. For example, 127.5 degrees
is read or written as 1275 degrees with the decimal
parameter set to 0.0.
Parameters relating to communications appear in
the Output 4 Menu (Setup Page). Match the Baud
Rate [baUd] to that of the computer and select an
Address [Addr] for the Series 96.
NOTE: For more information about communicating with
Watlow controllers, go to www.watlow.com and download
the Data Communications Reference: Electronic User’s
Manual. It is located under Literature, User’s Manuals,
English and search on data communications reference.