Introduction
This article provides an overview of the available GRT1 Communication Units and their I/O Allocation specification.
I/O Allocation
There are restrictions on the number of SmartSlice I/O Units that you can connect to one Communications Unit.
The specification for each GRT1 Communication Unit is shown in the table below.
| Model name | GRT1-PRT | GRT1-PNT | GRT1-DRT | GRT1-CRT | GRT1-ML21 | GRT1-ECT |
| Network Specification | Profibus DP | PROFINET IO | DeviceNet | CompoNet | Mechatrolink-II | EtherCAT |
| Number of I/O data | ||||||
| Max. Input: | 128 bytes | 32 bytes | 128 bytes | 64 bytes | ||
| Max. Output: | 128 bytes | 32 bytes | 128 bytes | 64 bytes | ||
| Max. I/O Allocation: | 128 bytes | 64 bytes | 128 bytes | 128 bytes | ||
|
Number of I/O points |
1024 I/O | 256 Inputs and 256 Outputs |
1024 I/O | 512 Inputs and 512 Outputs |
||
|
Number of connectable |
Up to 642 |
|||||
Note 1: The GRT1-ML2 supports the GRT1-IA4-1, GRT1-IA4-2, GRT1-OD4G-3, GRT1-TS2P, GRT1-TS2K and GRT1-TS2T slice units only in combination with TJ2-MC64 motion controller. They are not supported in combination with TJ1-MC16/04.
Note 2: GRT1-END-M end plate for PROFINET name storage counts as a unit, it reduces the total amount of connectable SmartSlice I/O Units to 63.
Configuration examples
The following examples provide information about the I/O Allocation with GRT1 Units regarding permitted and bad configurations. These examples visualise what could happen with the I/O Allocation.
Permitted Configuration:
Note: GRT1-CRT used as coupler
- 2 bytes are used for CompoNet Communications Unit status
- Four-point DC Input Unit (GRT1-ID4): 4 bits × 12 = 6 bytes in Input Area
- Analog Input Unit (GRT1-AD2): 2 words (4 bytes) × 6 = 24 bytes in Input Area
- Total: 32 bytes in Input Area
The I/O Allocation is shown below.
Bad Configuration:
Note: GRT1-CRT used as coupler
- 2 bytes are used for CompoNet Communications Unit status
- Four-point DC Input Unit (GRT1-ID4): 4 bits x 6 = 3 bytes in Input Area
- Two-point Analog Input unit (GRT1-AD2): 2 Words (4 bytes) x 6 = 24 bytes in Input Area
- Total: 29 bytes + 9 unused bytes = 38 bytes in Input Area
A section of the unused bytes in the I/O Allocation are shown below.
The reason that bits 4 to 7 are not used and the GRT1-AD2 does not start at byte 3 is that: “I/O Units with bit allocations (such as the GRT1-ID4/OD4) are allocated data in 2-bit units. I/O Units with word allocations (such as the GRT1-AD2) are allocated data in 1-word units and are allocated at even byte boundaries.”
Please refer to chapter 2-2 Unit Numbers and I/O Allocations of Operation Manual ‘Slice I/O Units’ (Cat. No. W455-E1-06) for more details.
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