Pc Connection - McQuay MicroTech Installation & Maintenance Data

terminals in each of the level-2 controllers. Refer to the product-specific installation and maintenance
manuals to find the correct terminals.
Note that unit designations are established by the network address, not the physical position of the
unit in the daisy chain. Thus the networked controllers can be wired in any order. However, it is
highly recommended that the installing contractor keep track of the physical order of the controllers
on the daisy-chained trunk by preparing a schedule. This will facilitate troubleshooting any network
communications problems that may occur. For more on the network address, see "About the Network
Address" on page 15.
To perform the network wiring
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1.
2.

PC Connection

PC connection to the OPM Panel (or its substitute) is required to commission the network (see the
"Network Commissioning" section below). A laptop computer is ideal for network commissioning.
Table 5 shows the specifications for the PC.
During network commissioning, the PC should normally be directly connected to port A on the OPM.
Port A should be set up for RS-232 by setting the Port A Select switch above port A to "232." (If unit
controller troubleshooting is required, the PC can also be directly connected to the A port on any
properly configured level-2 controller.)
The OPM Panel's default port A communications rate is 9600 baud; however, it can be changed. See
the "Controller Information Screen" sub-section of the MicroTech Open Protocol Monitor Software
User's Manual for more information on changing the OPM's port configurations.
Direct Connection
An RS-232 communications cable kit that allows a PC to be directly connected to any MicroTech
controller is available from McQuay International. The part number is 0057186802. The cable has a
female DB-9 connector for connection to the PC's 9-pin serial port. (If the PC has a 25-pin serial port,
obtain an adapter.) The cable length is 12 feet. If more length is required, a twisted, shielded pair
cable can be spliced into the kit cable (see "Cable Specification" below). If this is done, splice the
conductors with crimp-type butt connectors (better) or solder (best). Do not use wire nuts. The
maximum allowable cable length for direct connection between the PC and a controller is 50 feet.
Cable Specification
A properly terminated, twisted, shielded pair cable is required to directly connect a PC to a
MicroTech controller. The cable must meet the following minimum requirements: twisted, shielded
pair with drain wire, 300 V, 60°C, 20 AWG, polyethylene insulated, with a PVC outer jacket (Belden
8762 or equivalent). It must also be properly terminated to an AMP or Phoenix plug on one end and a
female DB-9 or DB-25 connector on the other. See Figures 5 and 6 for cable pinouts. The OPM uses
a Phoenix-type connector. Several unit controllers and alternatives to the OPM Panel use an AMP-
type connector. The McQuay part number for the Phoenix connector shown in the figures is
497590B-01. The AMP part numbers for the AMP connector shown in the figures are as follows:
1-480270-0 (plug) and 60617-1 (female pin terminals). Note that some local codes or applications
IM 474-3
Before beginning, verify that the port B plug is disconnected from every controller on the
communications trunk being wired. These plugs will be connected during the commissioning
procedure. This is a precaution to prevent stray high voltage from damaging the controllers. Any
voltage more than 12 V can damage the board's communications drivers.
Connect the network cable in a daisy-chain manner as shown in Figure 4. Use caution to ensure
that the correct polarity is maintained at each controller. Be sure to connect each cable's shield to
the controllers as shown in the figure. The positive (+), negative (–), and shield (ground)
conductor must be continuous over the trunk.
Note: Refer to the product-specific installation and maintenance manuals to find the correct field
wiring connections (see Table 1 on page 3).
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