Special Link Relays (Sb); Step Relays (S) - Mitsubishi Electric MELSEC-Q Series User Manual

10 DEVICES

10.2.8 Special link relays (SB)

10.2.9 Step relays (S)

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(1) Definition
(a) A special link relay indicates the communication status and error detection
of an intelligent function module, such as the MELSECNET/10H Network
Module.
(b) Because special link relays are switched ON and OFF in accordance with
various problems which may occur during a data link, they serve as a tool
for identifying data link problems.
(2) Number of special link relay points
There are a total of 1024 special link relay points between SB0 and SB3FF.
Special link relays are assigned at a rate of 512 points per each intelligent
function module, such as the MELSECNET/10H Network Module.
REMARK
1) For details regarding special link relays used at the Basic model QCPU, refer to
the QCPU (Q mode)/QnACPU Programming Manual (Common Instructions).
The step relays are devices designed for SFC.
The step relays cannot be used for future expansion.
MELSEC-Q
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