YASKAWA SGMAS User Manual page 124

6 SynqNet™ Communications
6.2.3 Precautions for Wiring SynqNet Cables
In some servo networks, the system designer may want to optimize the packet spacing by configuring the cable
length values. Most networks will not need this type of optimization. The SynqNet network has maximum, mini-
mum, and nominal cable length configurations. Changing these configurations will affect the packet spacing cal-
culations and the topology mismatch checking. During network initialization, if a measured cable length is not
between the minimum and maximum values, a Topology Mismatch error will be returned.
A break-free cable performs much better than one with an in-line coupler. Even those couplers that offer continu-
ity of the shield do so in an inadequate fashion and should be avoided.
During network initialization, the nominal cable lengths will be measured and the minimum and maximum val-
ues will be calculated. The minimum cable length will be set to the nominal - 8 meters. The maximum cable
length will be set to the nominal + 8 meters. During subsequent network initializations, the measured cable
length will be compared to the minimum and maximum values. If the measured cable length is not between the
minimum and maximum values, a Topology Mismatch error will be returned. To recover, use a control reset to
clear the previous minimum and maximum cable values, re-initialize the network, and set the new min/max val-
ues.
(2) Micro-D Connections
SGDS SynqNet utilizes Micro-D connectors to interconnect the nodes and the controller. See section 5.3.4 Synq-
Net Connectors (CN6A and CN6B) for Micro-D pin arrangements. The cabling scheme uses straight through
cables. The crossover of transmit and receive is carried out at the connectors. These two pinouts have been
named the "OUT" port and the "IN" port to assist in the setup of hardware, but remember that each port is full
duplex and has the ability to transmit and receive data.
(3) Cable Shielding
SynqNet defines cable shielding conventions in order to properly isolate local node signals and power while min-
imizing EMI (both emission and reception). Shielded cabling will reduce EMI coupled from other devices in the
system. The cables shall have their shields connected to the metal connector shell using the clamp on the Micro-
D connector. Cable shield connections are treated slightly differently at the controller and node PCBs. Both are
detailed below.
Optional AC (Capacitor)
coupled to Digital GND
OUT PORT
IN PORT
6-6
ISOLATED PLANE
SHIELD GND5
D S
C2 C3
D S S
C5 C6
D S S
Controller Connector
(Tied to cable shell)
Cable Shell
(Tied to shield)
Cable Shield
Twisted Pair
(one shown)
Chassis or Bracket
Tied to Connector
(Tied to shield)