Hitachi EH-150 Series - Performance Specification

Chapter 6 Communication mode
6 - 89
Simple data link
6.6.2 Performance specification
Following table shows the performance specification of simple data link.
Table 6.25 Performance specification of simple data link
Items
Specification
Interface
RS-422
Maximum number of link communications
31 stations
Transmission cable length
500m / 250m
(*1)
Number of
link points
Per one station
Max. 48 words
Total stations
Max. 1,536 words
Data exchange
method
Between EH-SIO and CPU
Handshaking between CPU module and EH-SIO
(*2)
Between EH-SIO and slave PLC
Set/reset by using task code communication
Configuration of data area
By Master CPU module using TRNS9 command
(No configuration necessary for slave stations)
Transmission speed
4,800, 9,600, 19,200 or 38,400 bps
(*3)
Communication Protocol
H series dedicated procedure (Hi-Protocol)
Transmission procedure 2
Maximum mounted EH-SIO per CPU
8 units
*1 In case of simple data link communication between EH-150 CPU / EHV-CPU, maximum length is 500m and in case of
MICRO-EH / MICRO-EHV is 250m.
*2 Handshaking between CPU and EH-SIO will be done automatically by system software at the end of scan. It takes 6 scan
cycle time to transfer one station data.
*3 Transmission speed is configured by DIP Sw.
 Data refresh time
Data refresh time depends on scan time of master CPU, transmission speed, the number of slave stations and size of
data link area. The following is the formula of data refreshing time.
(1) Standard mode
{RReq + RRes + (WReq + WRes)  n + SWT  n + RWT  n + HST }  n
n : The number of stations
RReq : Transmission time of reading request from master to slave (depends on transmission speed)
RRes : Transmission time of reading response from slave to master (depends on capacity and transmission speed)
WReq : Transmission time of writing request from master to slave (depends on capacity and transmission speed)
WRes : Transmission time of writing response from slave to to master (depends on transmission speed)
SWT : Switching time from one slave to other slave station number (configured by user)
RWT : Slave station response time delay (configured by user)
HST : Handshake time between CPU module and EH-SIO (6 times of scan time)
Ex.) The number of stations : 31 stations, The number of link points : 48 words/master, 48 words/slave,
Transmission speed : 38.4 kbps, Switching slave time : 20 ms, Waiting time of slave response : 20 ms,
CPU scan time : 10 ms
{5 + 52 + (55 + 2)  31 + 20 x 31 + 20  31 + 60}  31 = 96844 [ms] ≒ 96.8 [s]
(2) High speed mode
( RReq + RRes + WReq + WRes + SWT + RWT + HST )  n
Ex.) The number of stations : 31 stations, The number of link points : 48 words/master, 48 words/slave,
Transmission speed : 38.4 kbps, Switching slave time : 20 ms, Waiting time of slave response : 20 ms,
CPU scan time : 10ms
(5 + 52 + 55 + 2 + 20 + 20 + 60) x 31 = 6634 [ms] ≒ 6.6 [s]