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8.4 WATLOW Series 988 User’s Manual
General Software Features, Chapter 8
General Software
Communications
Requirements
Choose which interface your application will use: EIA/TIA-232 serial com-
munications (98_ _-_ _ _ _-_R_ _), EIA/TIA-485 or EIA/TIA 232 serial com-
munications (98_ _-_ _ _ _-_U_ _), or EIA/TIA-485 or EIA/TIA-422 serial
communications (98_ _-_ _ _ _-_S_ _). The computer must have a compati-
ble serial port or an appropriate converter must be used.
Overview
The serial communications feature allows the Series 988 family to receive
commands from and transmit data to a master device, usually a comput-
er. Any function that can be performed via the front panel, can also be
accomplished using a serial communications port, allowing you to operate
the controller from a computer and to store process data on a computer.
L4 acts as the RX/TX indicator on the front display panel of the 988.
The Series 988 is available with a choice of serial hardware interfaces. An
EIA/TIA-232 interface allows for one master (computer) and one con-
troller, with a maximum network length of 50 feet (15 meters).
The EIA/TIA-485 or EIA/TIA-422 option equips the controller for a multi-
drop interface: up to 32 total network devices with EIA/TIA-485 and up to
10 total network devices with EIA/TIA-422. Each controller will have its
own unique address. The total maximum network length is 4,000 feet
(1,219 meters). All interfaces are isolated.
To select between EIA/TIA-485 or EIA/TIA-422, enter the Setup Menus by
holding the up-arrow > and down-arrow < keys simultaneously until
setup [`SEt] appears in the bottom display. Use the up-arrow key to
select the Communications Menu [COM]. At the interface prompt [Intf]
select between [`422] or [`485].
Other parameters that must be configured in the Communications Menu
[COM] are the baud rate [bAUd], data bits and parity [data], protocol
[Prot], and device address [Addr]. The protocol prompt must be set to
full (ANSI X3.28 2.2-A3) or RTU Modbus if multiple devices are used with
the EIA/TIA-485 or EIA/TIA-422 interface. If the full protocol or RTU
Modbus is selected, a device address must be selected at the address
prompt. For EIA/TIA-232, full [FULL] or on [``on] (XON/XOFF) protocol
may be selected.